On my piano, I have a couple keys which regularly become sluggish, and don't want to lift up. As I'm playing very fast music, I don't have time between playing on the sluggish keys and coming back to them for them to lift back up on their own; so I often find myself having to stop and un-stick the key, which becomes stuck again as soon as I play it.
Does anybody else have this problem? If so, what did you do?