Order, entered on August 16, 1961, denying plaintiff’s motion for summary judgment under rule 113 of the Rules of Civil Practice, in this action upon a written guarantee, unanimously reversed, on the law, with $20 costs and disbursements to the appellant, and the motion granted, with $10 costs. Leave is granted, however, to defendants to move within 30 days of the service of the order herein to vacate the order and any judgment thereon upon affidavits showing facts establishing a counterclaim for reformation of the guarantee. There is no dispute that defendants signed and delivered the written guaraní; e, and, whether it be a complete or *889only a partial integration of the understanding among the parties, it cannot be varied or contradicted by parol evidence (Laskey v. Rubel Corp., 303 N. Y. 69; Restatement, Contracts, § 239; 3 Corbin, Contracts, § 581). Confining the written guarantee to the pre-existing obligation, as defendants sock to do, would contradict the express language of the writing. It may be, however, that defendants would be able to plead, and to establish by “ clear, positive and convincing evidence”, that the writing should be reformed on the ground of fraud or mistake (see Amend v. Hurley, 293 N. Y. 587, 595; Restatement, Contracts, §§ 504, 505; 6 N. Y. Jur., Cancellation and Reformation of Instruments, §§ 22-51, especially §§ 29, 41-49). If so, they should be given an opportunity to do so and, thereby, to avoid summary judgment. Settle order on notice. Concur — Breitel, J. P., Valente, Stevens, Eager and Steuer, JJ.