I'm not noob enough not to realize the rarity of parts for the 2400c. I have another one with a bad power board that I need to fix and/or replace. Any thoughts on what may be bad on that?

I'm only experimenting because I have a processor board with a bad processor. I'm good enough that I can remove and replace the bad chip with a faster one, thus I would like to know how to change the clock frequency accordingly. No sense using a 300MHz 603e if it'll only run at 180MHz (although it might run comparatively cooler than the original).

No spare keyboards, I'm afraid. Except for my close-to-pristine prototype model, all of my 2400 keyboards are noticeably worn anyway.