1. All causes of action, other than actions for relief on the grounds of fraud or mistake, against a state credit union based upon a claim or claims founded on a written contract, or a claim or claims inconsistent with an entry or entries in a state credit union record, made in the ordinary course of business, shall be deemed to have accrued, and shall accrue for the purpose of the statute of limitations one year after the breach or failure of performance of a written contract, or one year after the date of such entry or entries. No action founded upon such a cause may be brought after the expiration of six years from the date of such accrual.
 2. In any cause or proceeding in which state credit union records or files may be called in question or be demanded of the state credit union, or any officer or employee of the state credit union, a showing that such records or files have been destroyed in accordance with the provisions of this chapter or rules adopted pursuant to this chapter shall be a sufficient excuse for the failure to produce them.