Loose flange on let up? NOT

[Baldwin Yamaha Piano Centre]

Hi Mike,
          Two more thoughts after your clarification. Point one, the
knuckles not solid in the mortice slot can cause this problem, they can
appear tight but the only sure way is to pull one and reglue.
Point two, those teflon bushings (hammer flange) can make a hell of a
racket, with very little feelable motion, a quick check is to raise the
hammers to the horizontal,let drop and observe the bounce. if there is
more bounce than the other notes you have isolated the problem. Wippen
flanges seem to be able to wear to a greater degree with out causing the
problem that you have mentioned.
 If you switch the hammers first it will isolate shank from wippen as
the cause of the problem.
Have a nice day.
Roger Jolly.