Appellant Rose Maree Jones, formerly a United States Customs Inspector in Montana, appeals from the denial of a motion for a new trial following an adverse jury verdict in her products liability action against Appellees Athea Laboratories and Aero/Chem Corporation (collectively “Athea”), assembler and distributor of the “Curb 20,” a hand-held aerosol tear gas spraying device.

*877 Jones was required to wear the Curb 20 tear gas canister in a holster on her duty belt. While Jones was inspecting a truck, a fold-up armrest fell and struck the top of the Curb 20 unit, discharging the tear gas above her hip. Jones suffered a chemical burn and developed allergic dermatitis which prevented her from returning to work.

The cause went to a jury which returned a special verdict finding “no defect” in the Curb 20. Two days later, counsel for third party defendant Emson Research Company (“Emson”), manufacturer of the component valve and actuator systems, gave counsel for Jones copies of correspondence from Athea to Emson, including a March 20, 1981 letter written by Gary Smith, engineer and Vice President of Athea. Smith’s letter indicated Athea considered the actuator system “too sensitive,” knew of the possibility of accidental discharge, and discussed remedial measures. 1

The following day, Jones moved for new trial pursuant to Fed.R.Civ.P. 59, asserting: (1) the newly discovered evidence; (2) prejudicial misconduct in failing to produce the documents in discovery; (3) error in admitting testimony of the absence of prior complaints; and (4) error in admitting testimony that California had approved the Curb 20. At the hearing on the motion, the district court indicated it might later hold a hearing to determine whether Athea’s failure to produce the documents involved misconduct. However, the district court denied the new trial motion without holding such a hearing. Jones appealed.

I. The “Hidden” Documents

Our review of the record indicates Jones asked the district court to make two determinations: (1) whether a new trial should be granted because the newly discovered evidence would likely have resulted in a different verdict, and (2) whether defendants’ actions constituted misconduct and, if so, whether that misconduct denied Jones an opportunity to present her case fully and fairly. 2

*878 a. Newly Discovered Evidence.

In deciding the Rule 59 motion, both parties argued and the district court applied the test borrowed from cases considering motions under Rule 60(b)(2) for relief from judgment based upon newly discovered evidence. See 11 C. Wright & A. Miller, Federal Practice and Procedure: Civil § 2859 (1973) (“The same standard applies to motions on the ground of newly discovered evidence whether they are made under Rule 59 or Rule 60(b)(2).”); 7 J. Moore & J. Lucas, Moore’s Federal Practice ¶ 60.23[4] (2d ed. 1987) (distinction between evidence warranting Rule 59 and Rule 60(b)(2) relief is one of degree rather than kind; Rule 60(b)(2), allowing a more belated attack on a judgment, may require a stronger showing); Coastal Transfer Co. v. Toyota Motor Sales, U.S.A., 833 F.2d 208, 211-12 (9th Cir.1987).

Under this test the movant must show the evidence (1) existed at the time of the trial, (2) could not have been discovered through due diligence, and (3) was “of such magnitude that production of it earlier would have been likely to change the disposition of the case.” Coastal Transfer, 833 F.2d at 211 . We review the district court’s determination under this standard for abuse of discretion. Id.

The court determined Jones met the first two requirements, but did not satisfy the third. The court concluded it was not likely the documents would have changed the outcome because they only corroborated testimony by Jones’ expert. They would have been of de minimis value in light of the theory of defect Jones presented at trial: the Curb 20 was too sensitive in the locked position or moved too easily from the locked to the fire position.

Whether knowledge of the newly revealed correspondence would likely have affected the jury’s verdict is a close question. Contrary to the district court’s view, we think the letters do more than merely corroborate plaintiff’s expert testimony; they demonstrate knowledge by Athea of a potential design problem. An admission by the company engineer that the valve was “too sensitive” is substantively different than testimony to that effect by the plaintiff’s own hired expert.

However, the letters are not equivalent to a “smoking gun,” as Jones argues. Rather than dictating a different result, they would likely have led Jones to prepare and present a different case—taking additional depositions, presenting other witnesses, and arguing a different theory of defect to the jury. Althea, too, would have defended differently. We are not persuaded, however, that the district court abused its discretion in concluding Jones failed to establish the outcome likely would have been different.

b. Misconduct.

The test to be applied when discovery misconduct is alleged in a Rule 59 motion must be borrowed from cases interpreting Rule 60(b)(3), just as the test applied to a Rule 59 motion alleging newly discovered evidence is borrowed from Rule 60(b)(2). 3

Under Rule 60(b)(3), the movant must,

Bunch v. United States, 680 F.2d 1271, 1283 (9th Cir.1982) (citation omitted). Moreover, as the court said in Anderson v. Cryovac, Inc., 862 F.2d 910 (1st Cir.1988):

Id. at 923. The court in Anderson found misconduct within the meaning of Rule 60(b)(3) because plaintiffs demonstrated (1) they exercised due diligence in their discovery requests, (2) defendant knew, or was charged with knowledge, of the missing document, and had constructive (if not actual) possession of it; and (3) defendant did not divulge the document’s existence. Id. at 928 .

Regardless of whether there was misconduct, Athea argues this court should find the letters cumulative, corroborative and of de minimis value under the Rule 60(b)(3) test of “full fair opportunity to present one’s case” based on the district court’s finding to that effect under the Rule 60(b)(2) “different outcome” test. We disagree. If Jones is able to demonstrate misconduct, the district court must make a fresh determination whether Jones has demonstrated “substantial interference” by showing “the material’s likely worth as trial evidence or by elucidating its value as a tool for obtaining meaningful discovery.” Id. at 926 . As noted earlier, the letters were much more than merely corroborative or cumulative evidence. And, further, as we also have noted, evidence that was merely cumulative under the “different outcome” test, may have substantially interfered with Jones’ ability to fully and fairly present her case—for example, concealment of Athea’s statement the valve was too sensitive may have “precluded inquiry into a plausible theory of liability.” Id. at 925 . Additionally, Jones may be able to benefit from a presumption of substantial interference if she can demonstrate the misconduct was sufficiently knowing, deliberate or intentional. See generally id. at 923-27 (summarizing the applicable standards and burdens of proof).

It does not appear the district court considered the alleged misconduct in deciding Jones’ Rule 59 motion; the district court did not hold a hearing to determine whether there had been misconduct, either knowing or accidental, nor did it make findings on this issue. 4 We therefore remand to the district court for appropriate proceedings to determine whether Jones can meet her burdens under the Rule 60(b)(3) standard as applied to this Rule 59 motion. 5

II. Evidentiary Issues

a. Jones argues a proper foundation was not laid for the admission of testimony of Althea’s employees that Althea had not received complaints from customers that the Curb 20 accidentally discharged or that the actuator accidentally *880 moved from the locked to the firing position.

The district court’s finding that the three-quarters of a million Curb 20 units sold from 1979 onward were substantially identical, despite slight variation from unit to unit, was not clearly erroneous. The court did not err in determining the absence of reports of prior accidents occurred in circumstances sufficiently similar to Jones’ situation to allow the jury to connect past experience with the accident sued upon. Substantial evidence supported the trial court’s finding that the witnesses who testified on the subject were in a position to know of any complaints regarding the Curb 20. Jones’ argument that the testimony regarding lack of complaints was factually untrue in light of the “hidden” letters and the existence of another civil complaint goes to the weight of the testimony, not its admissibility. Of course, one of the considerations in ruling on the Rule 59 motion will be the possible impact the letters might have had in countering this evidence in the jurors’ minds.

In sum, the district court did not abuse its discretion in concluding there was sufficient foundation evidence to admit the testimony regarding lack of complaints to rebut Jones’ claim the Curb 20 was defectively designed.

b. Jones also appeals the admission of testimony suggesting California had specifically approved the Curb 20. The witness’ reference (“when California came out and approved the product for use by civilians”) is ambiguous as to whether the witness was referring to tear gas products in general or the Curb 20 specifically. Moreover, even if the reference were to the Curb 20, it was insignificant in the context of the whole record and its admission, if error, was harmless.

REVERSED AND REMANDED. 6

. The March 20, 1981 letter was apparently written in the context of a redesign of the actuator system after Emson had switched from a .010 to a .075 actuator length stem valve and thus rendered the Curb 20 too difficult to fire. In discussing possible solutions, Smith wrote:

In an October 5, 1981 letter from Smith to Emson, accepting Emson's revised sleeves for the .075 units, Smith concludes,

. We conclude Jones has not waived the misconduct argument.

In her motion for a new trial Jones argued defendants' conduct "in illegally hiding such documents prevented plaintiff from putting on her proof of defect and prevented her from receiving a fair trial.” [C.R. 135 at 2-3] In her memorandum in support of her Rule 59 motion, Jones noted the alleged misconduct was a separate ground for relief from that of newly discovered evidence, and argued defendants had “stripped plaintiff of the right to a fair trial,” [C.R. 136 at 4-5] citing 6A J. Moore, J. Lucas, & G. Grotheer, Moore's Federal Practice ¶ 59.08[2] (2d ed. 1987), discussing new trial motions based on party misconduct. Finally, in her appellate brief Jones argued:

Appellant’s Brief at 35-36.

Jones first argued that a different, more lenient test was applicable to the misconduct claim in a supplemental letter filed following briefing. As a general rule, we will not consider an issue raised for the first time on appeal, although we have power to do so. Bolker v. Commissioner, 760 F.2d 1039, 1042 (9th Cir.1985). Neither will the court normally consider *878 an issue not argued in the opening brief. United States v. Loya, 807 F.2d 1483, 1486-87 (9th Cir.1987).

On balance, we conclude it would be appropriate to exercise our power to review the misconduct issue. Jones did present the core of the legal analysis to the district court in asking the court to hold a hearing to determine if there was misconduct, and if so, whether that misconduct had interfered with her right to a fair trial. Defendants’ counsel did not object to consideration of the issue by this court or argue that it had been waived, choosing instead to assert that the defendants should prevail under the Rule 60(b)(3) standard.

. Although we have found no case discussing the applicable standard where discovery misconduct is alleged in a Rule 59 motion, the analogy seems inevitable: if, when misconduct was alleged, a stricter standard were applied to a motion under Rule 59 than to one under Rule 60(b)(3), a plaintiff filing within the 10 day period might be unable to obtain a new trial but could thereafter be relieved from the judgment under Rule 60, and thus allowed to begin the litigation all over again.

. It is understandable the district court did not hold a hearing or make findings on whether misconduct had occurred and if so, whether it denied Jones a full and fair trial since the Rule 60(b)(3) standard was not expressly called to the district court's attention. Nonetheless, for reasons stated in note 2, we conclude Jones has not waived the misconduct argument.

. The district court stayed its consideration of Jones' motion for discovery sanctions pending decision by this court on the substantive appeal. We note the district court’s finding on the new trial motion is not co-extensive with its determination of the discovery sanctions motion. Discovery misconduct may be sanctionable whether or not it justifies a new trial. Id. at 924 n. 11.

. During the pendency of this appeal, Jones moved to stay these proceedings and remand to the district court to allow her to file a Rule 60(b)(6) motion based upon additional allegedly "hidden" documents she has recovered. This opinion moots Jones’ motion to stay and remand.

On remand, Jones may file her Rule 60(b)(6) motion in the district court. We express no opinion whether such a motion could be timely, see LaFarge Conseils et Etudes, S.A v. Kaiser Cement & Gypsum Corp., 791 F.2d 1334, 1338 (9th Cir.1986); but see United States v. Sparks, 685 F.2d 1128, 1131 (9th Cir.1982), or if timely, whether the circumstances are sufficiently extraordinary to merit relief.