(1)    “Alteration” means an unauthorized change in an instrument that purports to modify in any respect the obligation of a party or an unauthorized addition of words or numbers or other change to an incomplete instrument relating to the obligation of a party.

   (2)   Except as provided in sub. (3), an alteration fraudulently made discharges a party whose obligation is affected by the alteration unless that party assents or is precluded from asserting the alteration. No other alteration discharges a party, and the instrument may be enforced according to its original terms.

   (3)   A payer bank or drawee paying a fraudulently altered instrument or a person taking it for value, in good faith and without notice of the alteration, may enforce rights with respect to the instrument according to its original terms, or, in the case of an incomplete instrument altered by unauthorized completion, according to its terms as completed.