I recently bought a 2nd-hand upright piano and had it tuned after a couple of weeks. The tuner (who came well recommended) says he got it up to concert pitch.
However I noticed one key in particular - about an octave and a half about middle C - causes a nasty whining buzz. It's reminiscent of a dentist drill almost. The note itself seems in tune and opening the lid doesn't make it stop (I thought it could be a buzz).
What could cause this? It's maybe only noticeable to the player but it's a key that gets a lot of use. Could it be a tiny issue in the tuning between the strings on that key - it seems too high-frequency to me personally? Or does it suggest something is loose?
The tuner man did say that it's really only when he does a 2nd tuning on a piano he can see which strings have particular issues (which pegs slip, etc) and I'm loath to get him out just for this one issue.