I had discovered this issue before coming across this thread. I performed a similar fix. I play strictly through headphones due to being mostly in a common room where other people are (spouse) and the key noise has gotten progressively louder over time. To the point that I was hearing it through my headphones. The thumping wasn't so bad but the release noise bouncing clackity was getting worse. Especially across the broad middle of the keyboard high traffic area.
I purchased these felts from Howard piano where I have picked up other piano supplies. I already had a temperament strip and did a non glued test and that seemed to be the perfect thickness to rest firmly on the keys without pressing down on them. As I discovered that even a small amount of downward compression will alter impact of the top sensor which affects playability. The reason I bought 2 thicknesses is due to a discovery that the gap in the top cover where the blue felt is attached, is not a uniform width above the keys across the length of the keyboard. It is thinner at the last 2" of either end causing a slight compression that I described. I used the thinner felt for the end keys hiding the transition behind the highest Bb. I was unable to do that on the lower end so it shows a little (measure twice cut once). Not a big deal to me as I don't notice it to much but for anyone else doing this take note. All three pieces were CAREFULLY attached with a thin line of contact cement to the blue felt by laying the red felt across the keys keeping it aligned to the back of the black keys, laying a bead of cement on the red felt, and then carefully lowering the top cover in place and gently pressing down. there is a short time to adjust the new felt before it becomes more solidly affixed.
I did have to trim the width of the temperament strip to a more consistent 1/2" for the full length so it wouldn't interfere with the top cover screw mounts. I left a reveal up to the back of the black keys. I kind of like the look of the red against the blue. Reminds me of my '83 VW GTI dashboard. This has made a big difference for me though there is still some wiggle room in the keys due to how they are looped around the action underneath. I may investigate a fix for that in the future.
Name board felt .058" thick @ $2.95 U.S.
Temperament strip - 50" long and is tapered from 3/4" down to 1/2" .125" thick @ $4.50 U.S.
Brian
