Bouncing hammers.

[Ron Nossaman]

>How can I avoid this problem? Why is it doing it only in the bass?
>
>Victor

Sounds like you're getting a trampoline effect from the springy rail with
the heavy hammers. If all else fails,  try replacing the rest felt, and you
might even put a leather washer between the rail and the nuts as a damper.
If that helps, but not enough, make a stiffer rail. If that doesn't help at
all, never mind.

Ron N