bobble heads rule(r)

[Jon Page]

I've forgotten the context of the original post.
Just what is causing the bobbling?
    I know that's the jist of the question...But...

Are the hammers merely slipping out of check
or
are the jacks not sufficiently clearing the knuckles.

One thing comes to mind.  Inspect the length of the rep spring which enters 
the jack.
I've found these to be too long, jamming into the jack causing tensioning 
problems and
smooth jack operation.  If the jack is bound in this fashion, it can not 
trip out properly.

Also examine the curvature of the spring, especially in the rep lever, too 
abrupt of a curve
does not offer as fine a tensioning gradient as a longer spring arm.

Jon Page