Kawai hammer chattering

[grimlinda]

I don't know if "chattering" is the right term, but my Kawai baby grand (about 8 years old) started making a rather nasty sound when keys in the bass (2 C's below middle C up to about middle C) are released. It's as if the hammer is bouncing before coming to rest. Any suggestions?

[PianoGuy]

The hammer rest rail is held in place by a pair of lock-nuts one below (to regulate height of the rail) and one above to clamp it tight. The rail runs from bass to treble the length of the action. I suspect the bass end or middle register upper locknuts have come loose.

Two minute job for your tuner on his next visit.