Clicking black keys on a Kawai CN21 digital piano

[bobbys]

Just some of the black keys have a clicking noise and it when I move them laterally. Almost like there is a lack of side to side cushioning when they travel vertically.

The white keys are fine though there is significant key return noise. What's a cheap option for felt? I've heard of people using weatherstripping. Any recommendations? Or maybe buying it from Kawai isn't so expensive? Would be nice to bring it back to the well cushioned, muffled,  sound of new. There's (I think) 5 different felt strips on it. 1 for each side of the white and black keys and the red one for under the keyboard case.

I extracted the key structure out of the piano OK though I didn't realize there was a tiny wire on the right that plugs in!  Watch out for that, Kawai owners.  Soldering is no fun! I'm unclear on how to get at the keys.  I suppose unscrew the brown circuit board which probably has the key sensors?

Just realized how dangerous it could be, when a piano is disassembled, to leave the key structure upside down, once removed from the case. This will cause the black keys to compress their felt. If you're working on the piano it could really affect things having all that pressure compressing the felt with no letup for several days. I suppose a proper technician would have a way of suspending it so they could work on it upside down but the black key felts wouldn't be compressed.

Is there a disassembly manual? The owner's manual is useless. I think I need to check to see if the weights on the keys are rattling. But why would only some of the black keys have that clicking noise? Maybe the white keys are just supported better vertically by their inherent shape?