Upright Damper Regulation

[Bonifield-Poulson]

I am in the final stages of regulating the action on a Vose & Sons
upright that I have reconditioned (new felts, springs, etc.) and am
stumped by a problem that has cropped in regulating the dampers, in
particular the bass section.  This action has the usual two piece
damper lift rod, splitting at C3. The bass dampers are regulated so
that they lift evenly from the bass damper pedal, which of course
operates from the bass or left side of the action.  However, when the
full damper pedal (right) is operated, the bass dampers lift late and
in a bow-shaped pattern.  The first and last dampers of the bass
section lift with the treble dampers, with the dampers in between
lifting afterwards.  The bass lifter rod is straight, as are the
hanger hooks.  I'ver tried varying thicknesses of replacement leather
between the rods, which only change the timing of the lift, not the
pattern.  Any ideas?    Patrick Poulson, RPT