I recently took out the action on my grand piano to fix some clicking noises. There were two issues I fixed:
I noticed the screws behind the wippen were extremely loose and a loud clicking noise would occur if I tapped on the back of the key. I tightened the screws and the clicking noise stopped.
The hammer heads were loose, so I used a very small amount of glue so the hammer heads wouldn't move around so much. I stuck out my hand and hit it with the hammer a bunch of times to see if a clicking noise would occur, but one didn't.
After doing this I put the action back in the piano; however, a clicking noise still occurs on some of these notes! I thought maybe it's because the screws had immediately loosened, but they haven't. Additionally the clicking noise doesn't occur after I take the action out of the piano again.
What could be wrong?