I just bought this used and was going to give it to my father in law as a present. I didn’t realize till I got home that there is a bad key, but this key doesn’t exhibit issues I’ve seen in most repair videos. It actually sits higher than it should and clacks when depressed. I’m confident I can open this up an repair it but I want help identifying all the parts I’ll need. Please see the linked video showing the behavior and location.
It’s hard to say for sure without opening the keyboard up and looking, but my guess is that the lowest black note is either broken or simply loose. While most keys on the P125 are part of a group, that lowest black key is an individual piece, and it is this part:
Style 64U key, lowest black note - Syntaur