Bunch appeals from the judgment of the district court in an age discrimination action and from the denial of his motion to strike testimony, or alternatively for a new trial or for relief from judgment. We must decide whether the district court erred in denying Bunch’s motion; and, if so, whether the record shows prejudice. We find no error and no prejudice. We affirm the judgment and ruling of the district court.

I. FACTUAL BACKGROUND

A. Selection Process

In 1973, there was an opening at McChord Air Force Base in Washington for a position as an Air Force Reserve Technician (ART) Flight Instructor (Fixed Wing). Two candidates were considered for the position, Bunch and Charles Casson. Their records were reviewed and each was interviewed. After this preliminary process, Bunch was recommended as the primary nominee and Casson was selected as the alternate nominee. In keeping with the ART selection procedures, these recommendations were submitted to the Headquarters Air Force Reserve (AFRES) at Warner Robbins Air Force Base in Georgia.

At AFRES, the military records, including Officer Evaluation Reports (OER’s), and the educational backgrounds of both candidates were reviewed by the Operations Division and by the Civilian Personnel Division. The Operations Division concurred in the McChord Selection of Bunch. The Civilian Personnel Division, however, concluded that Casson was the superior candidate. This determination was made by Lee Lin-gelbach, Director of Civilian Personnel, and Pierce Duane Turner, his assistant. AFRES accepted the Civilian Personnel Division’s recommendation of Casson over Bunch. Bunch was notified of this decision by letter in April, 1973. The letter, drafted by Turner and signed by Lingelbach stated:

Plaintiffs Exhibit 8.

On April 12, 1974, Bunch filed suit in the district court alleging a violation of the Age Discrimination in Employment Act, 29 U.S.C. § 633 (a) [ADEA], Bunch contended that failure to select him for the position was on the basis of age and retainability which constituted age discrimination in violation of ADEA. See Brief for Appellant at 23. The suit was dismissed by the district court for lack of jurisdiction. On appeal we reversed concluding that jurisdiction existed since the suit was pending at the time the statute became effective. Bunch v. United States, 548 F.2d 336, 340 (9th Cir. 1977).

B. The Deposition Testimony

The depositions of Lingelbach and Turner were taken in October, 1978, by telephone. It is this deposition testimony that gives rise to Bunch’s claims on appeal before this court.

1. The Lingelbach Deposition

At the time Lingelbach was deposed, he had not recently reviewed all the documentation involved in the selection of Casson over Bunch. Lingelbach Deposition at 6. While he had a general recall of the selection, over five years had elapsed since the selection had been made. See id. at 5-6. During the deposition, Lingelbach gave the following responses to questions from Bunch’s counsel:

Id. at 11-12.

Id. at 27-29.

Lingelbach also testified that Casson was chosen for the ART position because he was better qualified on an overall basis:

Id. at 26.

2. The Turner Deposition

Turner had reviewed material concerning the Casson selection over Bunch shortly before he gave his telephonic deposition. Turner Deposition at 5-6. Turner was asked to explain the letter sent to Bunch informing him that he had not been selected:

(Discussion off the record.)

Id. at 26-29.

Turner testified that the retainability of both candidates was an “important consideration” in the decision, id. at 44, and that age was considered in relationship to retain-ability. Id. at 48. Turner also stated that he was aware Casson’s OER’s were higher than Bunch’s OER’s. Id. at 47. Turner could not, however, identify any one factor that was more important than any of the others in the selection of Casson. Id. at 44.

Neither Turner nor Lingelbach was asked what weight was given to any specific factor.

C. The Trial

The government’s theory of defense was that Bunch’s age was not the determining factor in the decision to select Casson for the ART position. Prior to trial, the pretrial order included the government’s contention that:

Brief for Appellee at 10. The pretrial order also stated that “on the overall, Casson had superior OER’s than did plaintiff.” Id.

In the government’s opening statement, counsel clearly set forth its theory that age was not the determining factor in the selection of Casson over Bunch:

RT at 8-11.

At the close of Bunch’s case, the government moved for entry of judgment on the ground that Bunch had failed to prove a claim for relief. RT at 56. The trial judge denied the motion and the government went forward with its case. RT at 65. Lingelbach testified that in selecting Cas-son over Bunch, the primary consideration was the quality of experience: “Well about fifty percent of our decision is based on what the quality of the man’s experience is, how well he has performed for everybody else up to this point.” RT at 108. This factor is demonstrated by the OER’s. RT at 103-04. Twenty-five percent of the decision was based on educational background, amount and kind. Id. at 104. The remaining twenty-five percent was a catchall category that became significant when comparing two individuals only if they were equal in the first two categories. See id. at Í04-05. Lingelbach testified that Casson’s OER’s were significantly higher than Bunch’s OER’s. See id. at 109-10. Moreover, Bunch’s military record indicated that he had been passed over (not promoted) twice during his active military duty. Id. at 112. Bunch’s educational experience was in chemistry and economics and he had not achieved a bachelor of science degree. This was compared with Casson’s educational experience which had resulted in a bachelor of science degree in aeronautical administration. Lingelbach indicated as important the fact that Bunch’s experience was not in a field related to aeronautics whereas Cas-son’s was. Finally, Lingelbach testified that retainability was really not significant in the choice of Casson over Bunch because of the other factors: “Casson obviously had the best record, he obviously had the greatest growth potential, and he had the longest period to grow in.” RT at 123.

On cross-examination, Lingelbach maintained his position that age and retainability were not the reasons for Bunch’s failure to be selected:

RT at 151-52.

On cross-examination, counsel for Bunch asked Lingelbach about portions of his deposition testimony:

RT at 139-41.

At the completion of Lingelbach’s testimony the government renewed its motion for entry of judgment. RT at 158. Bunch advised the court, however, that he had rebuttal evidence and the judge allowed Bunch to proceed. Id.

Bunch called Turner to the stand and asked him if he had heard Lingelbach’s testimony:

RT at 160-61.

Turner indicated, as had Lingelbach, that the OER’s were very important in Casson’s selection:

RT at 173-74.

Counsel for Bunch went on to ask Turner about his memory , now as compared to at the time of his deposition:

RT at 174-75. Turner was then questioned about specific portions of his deposition testimony:

RT at 176-78.

Turner then explained what he had meant during his deposition when he had referred to retainability as a factor in Cas-son’s selection.

Before judgment was entered in the case, six days after completion of the trial on September 8,1980, Bunch filed a motion for an order striking the testimony of defendants’ witnesses Lingelbach and Turner, a new trial, or relief from judgment. This motion was brought pursuant to Fed.R. Civ.P. 26(e), 59, and 60. On October 1,1980, the district judge denied Bunch’s motion and ordered judgment to be entered for the government. Judgment for the government was filed on October 7, 1980.

II. ISSUES

These facts raise the following issues:

A. Did the district court err in denying Bunch’s motion to strike the testimony of Lingelbach and Turner, or alternatively, for a new trial, or for relief from judgment.

B. Assuming that the motion was improperly denied, does the record show prejudice?

III. DISCUSSION

A. Propriety of the Motion

1. Denial of the Motion to Strike Testimony

Bunch contends that his motion to strike testimony or for alternative relief should have been granted as a sanction for a violation of Rule 26(e). Opening Brief for Appellant at 19. He argues that “the testimony of Lingelbach and Turner at trial constituted a major change in previously disclosed information and a major change in the defendant’s theory of defense.” Id. at 21. The government thus had “at least the minimal responsibility of notifying plaintiff of the change or supplementation of the information provided in discovery.” Reply Brief for Appellant at 12.

The determination of a violation of Rule 26(e) and the imposition of sanctions is left to the sound discretion of the trial judge. Phil Crowley Steel Corp. v. Macomber, Inc., 601 F.2d 342, 344 (8th Cir. 1979). The ruling of the district court will be reversed when there has been a gross abuse of discretion. See Scott & Fetzer Co. v. Dile, 643 F.2d 670, 674-75 (9th Cir. 1981). We must thus determine first whether the deposition responses of Lingelbach and Turner were no longer true, and second, if no longer true, whether the government’s failure to amend the responses was a knowing concealment.

First, the testimony of both Lingelbach and Turner throughout their depositions was that the decision to select Casson was not based on age but rather based on the whole-man concept; the decision to get the best person for the job taking into account all the factors that influence a person’s performance. See, e.g., Lingelbach deposition at 27-29; see also Turner deposition at 26-27. This testimony was consistent with the letter sent to Bunch in which it was stated that since Bunch did “not meet the ‘whole man’ qualification criteria” that Cas-son had been selected. Plaintiff’s Exhibit at 8. The testimony was also consistent with the government’s theory in the case that age was not the determining factor in the decision not to select Bunch. The government’s trial brief stated that: “The evidence at trial will show that age was but one factor taken into consideration and that other factors played as significant a role in plaintiff’s non-selection.” Trial brief for government at 11. The government’s opening statement, again mapped out the theory that Bunch would be unable to prove that age was the determining factor in his non-selection. RT at 8-11. The trial testimony of Lingelbach and Turner supported the government’s theory as outlined in the opening statement. See id.

Bunch, however, focuses on specific trial testimony of Lingelbach and Turner. With regard to Lingelbach, for instance, he directs our attention to Lingelbach’s statement that factors other than age and re-tainability “were paramount to the extent in distinguishing the difference between the experience of this individual [Casson] to where while those things were looked at, they were not relevant to his [Bunch’s] non-selection.” RT at 151-52. Bunch invites us to compare this statement with Lingel-bach’s deposition testimony that he thought generally “retainability would be one of the key factors.” Lingelbach deposition at 27. Bunch also points to Lingelbaeh’s testimony at trial that the OER’s were the major factor in Casson’s selection. See RT at 103-04. At his deposition Lingelbach indicated that there was no single factor that was primary to the decision to hire Casson. Lingelbach deposition at 26. Turner’s testimony at trial and his testimony at his deposition were essentially the same as Lingel-bach’s. Bunch would have us believe that the same problem of untruthfulness exists as to Turner’s testimony.

The deposition testimony of both Lingel-bach and Turner was brought to the court’s attention when counsel questioned each of them about the statements they had made during their depositions. See, e.g., RT at 139-41, 174-78. The trial judge did not, however, believe that the previous deposition testimony of Lingelbach and Turner was untruthful. He did not view their testimony as stating that age and retainability were never taken into account:

RT at 181-82.

Bunch called Turner to the stand as a rebuttal witness but Turner agreed with Lingelbach’s testimony, e.g., RT at 160-61. Finally, we note that the trial judge found the testimony of Lingelbach and Turner, to be “entirely credible and reasonable.” Finding of Fact No. 21.

We agree with the trial judge. Bunch has not established that the responses given by Lingelbach and Turner at their deposition, were “no longer true”, as required by Rule 26(e).

Second, assuming Bunch had succeeded in demonstrating that the deposition testimony of Lingelbach and Turner was no longer true, Rule 26(e) only imposes a duty to amend a response when failure to disclose new facts “is in substance a knowing concealment.” Fed.R.Civ.P. 26(e)(2)(B); see also, Havenfield Corp. v. H & R Block, Inc., 509 F.2d 1263, 1272 (8th Cir.), cert, denied, 421 U.S. 999 , 95 S.Ct. 2395 , 44 L.Ed.2d 665 (1975). Bunch failed to present any evidence that there was a knowing concealment of new facts. To the contrary Bunch advised the trial court that the government must have been surprised by the testimony of Lingelbach and Turner:

Bunch’s Memorandum of Authorities in Support of Plaintiff’s Motion to Strike Testimony or for Alternative Relief at 7. [Bunch’s Memorandum of Authorities] (emphasis in original).

The trial judge did not abuse his discretion in denying Bunch’s motion based on Rule 26(e).

2. Denial of the Motion for a New Trial

Bunch has argued that his motion for a new trial is based on Fed.R.Civ.P. 59. See Reply Brief for Appellant at 13. This reference in his reply brief is the only reference to Rule 59 or any of its sections that Bunch makes.

Rule 59(a) of the Federal Rules of Civil Procedure provides that:

On appeal we review the judge’s ruling under Fed.R.Civ.P. 59(a) for an abuse of discretion. See Saint Paul Marine Transportation Corp. v. Cerro Sales Corp., 505 F.2d 1115, 1118-19 (9th Cir. 1974).

Bunch has failed to set forth any basis for relief under Rule 59, nor are we referred to any case authority in support of this contention. Bunch did not indicate to the court what additional evidence would have been presented if the court had granted his motion under Rule 59. The trial judge did not abuse his discretion in denying Bunch’s motion insofar as it is based on Rule 59.

3. Denial of the Motion for Relief from Judgment

Bunch also claims that relief from judgment is required under Rule 60(b)(3) for “fraud .. ., misrepresentation, or other misconduct of an adverse party .. . . ” We are referred to Rozier v. Ford Motor Co., 573 F.2d 1332 (5th Cir. 1978) in support of this claim. Bunch’s reliance is misplaced.

Rozier states that in order to bring a successful claim under Rule 60(b)(3) a party must:

Id. at 1339 .

Rozier also states that the judge’s decision on a Rule 60(b)(3) motion is reviewed for an abuse of discretion. Id. at 1346 . In the matter before us, Bunch has offered no evidence that the verdict was obtained by fraud, misreprestentation or other misconduct. The record also reflects that Bunch had a full and fair opportunity to present his case. It was clear that the government maintained throughout the pretrial proceedings and the trial that Bunch would be unable to prove age was the determining factor in Casson’s selection. Moreover, Bunch was permitted to use the alleged prior inconsistent statements to attempt to impeach Lingelbach and Turner. The trial judge did not abuse his discretion in denying Bunch’s motion for relief from judgment based on Rule 60(b)(3).

B. If Error, Was it Prejudicial ?

Assuming that an error was committed under one or more of the above Rules of Civil Procedure, Bunch must establish that such error was not harmless. Rule 61 of the Federal Rules of Civil Procedure provides that no error in any ruling or order by the court is ground for a new trial or otherwise disturbing a judgment unless refusal to do so is inconsistent with substantial justice: “The court at every stage of the proceeding must disregard any error or defect in the proceeding which does not affect the substantial rights of the parties.” See also United States v. 1,071.08 Acres of Land, 564 F.2d 1350, 1353 (9th Cir. 1977).

Bunch has not indicated in what manner his substantial rights were affected. As outlined above, Bunch was aware before trial that the government’s theory of defense was that age was not the determining factor in selecting Casson over Bunch. This defense theory was set forth in the pretrial order, the trial brief, and articulated during the government’s opening statement. During the government’s presentation of its evidence, Bunch raised no objection on the grounds of surprise nor did he raise any other claim based on any alleged change in the defense theory. Bunch did not object to the testimony of Lingelbach on his direct examination. As noted above, he had full opportunity to cross-examine Lingelbach thoroughly about deposition testimony. He also had the opportunity to question Turner, his rebuttal witness, about Turner’s deposition testimony. Bunch’s motion to strike their trial testimony or for alternative relief was not made until six days after the completion of the trial.

Bunch suggests that had Lingelbach and Turner not changed their position, the government “would have been in the position of defending the use of age/retainability as a determining factor in not selecting plaintiff for the job.” Opening Brief for Appellant at 27. This argument is woefully unpersuasive. First, the government has never taken the position that age or retain-ability was a determining factor in Casson’s selection. Second, the government need only show that age discrimination was not the determining factor. Cancellier v. Federated Department Stores, 672 F.2d 1312 at 1315 (9th Cir. 1982). Thus, Bunch had the burden of proving that, but for his age, he would have been hired. See id.

We find no reversible error. The judgment of the district court and the order denying Bunch’s motion are AFFIRMED.

. An ART Flight Instructor (Fixed Wing) is a civilian position. RT at 69. A person must, however, be a member of the Air Force Reserve. The time that an individual may remain in the Air Force Reserve is based upon his rank. For instance lieutenent colonels and below can only stay in the Air Force Reserve for 28 years before they are compelled to retire. The amount of time a person thus remains eligible for an ART position is referred to as retainability. See id. at 71-72. Upon retirement from the Air Force Reserve and ART Flight Instructor would continue to have a right to employment until eligible for Civil Service Retirement. During the interim between retirement from the Air Force Reserve and eligibility for Civil Service Retirement different work must be found for the Flight Instructor.