Yamaha jumping jacks

[Paul Chick (Earthlink)]

Subject: Yamaha jumping jacks

About 2 years ago, when I had been regulating for about 30 years, I was 
called in to solve this problem for a Yamaha dealership.  I 
think that it is improperly designed.
Steve Ganz

I'm coming in a little late on this but has any one checked the damper
timing?  As I understand it, the spoons can contact the damper levers too
soon and load the wippen with the damper spring too early which keeps the
jack too close to the butt on a light (slow) blow.  Adjust for a later
damper timing, even past 1/2 hammer travel, and see if this cures the
problem.

Paul C