List, Not too long ago, I completely rebuilt a Moore & Moore, grand, circa 1870. The original action frame did not have glides. After doing everything to the action and piano, I had the same problem. Short version: I installed action glides and necessary modifications to the keybed, adjusted and voila' the Bass hammer bouncing went away. So, you might check the key frame bedding, also. Other posts are also good areas to scrutinize. Regards, Joe Garrett, RPT, (Oregon)
This PTG archive page provided courtesy of Moy Piano Service, LLC