Hi Bob , I may be wrong but I'm almost certain that the actual keys can be removed and replaced and are available as a spare part .

Do you actually have the Kn7000 service manual ?
which shows all the component parts .

i live in the Uk so I would contact wd Greenhill if you want the e mail address just drop me a line .

The reason I'm sure the keys can be removed is because a friend of mine did it to his Yamaha PSR3000 and made it into a module .

Regards ....Giovanni