Just put my HHKB Pro back together after a good cleaning. Had a key that was sticking and also noticed that there was some "board chow" building up.
For those of you with black HHKB's, know that the black DOES wear off. I have some white showing through now on the keys, which surprised me...I had figured that it was black dyed all the way through. Oh well.
But it IS nice and clean now. The nice thing about the electrical capacitive switches is that all of the moving parts are submersible. If you desired, you could put out the electronics and throw it all in the dishwasher. (I opted for the kitchen sink)
Ahhhhh...there's nothing quite like a fresh, clean keyboard.