Have to agree with Trackrig. Take a flashlight and look in every cabinet and cubbyhole for any signs of water intrusion, mold, or mildew. If you find any the chance of wood rot goes up immediately. I know you said you assumed you would have to gut and rebuild the unit based on age, don't assume that, you could well find a unit still watertight.
Appliances are expensive, while most folks hope to get by, expect to have to eventually change them, at 22 years old, they are due for updates as they break down, and unless their failures are very minor, I would replace rather than repair.
