I used to play on a Casio CK3800 with the same clunk on the keys ( it was a great teaching 'board). So I got a strip of self adhesive foam to stop drafts in doors and windows and placed it along the base of the keyboard under where the keys hit the frame of the chassis. I didn't even lift the lid of the keyboard to install it. It went in and as far back as I could place it. Boy did it help quieten down that clunk - much better and a cheap fix.



Allan