Knabe keyboard/bed problem

[R Barber]

Customer has a Knabe Grand, around 6'6", ~80 years old.  In highest 
octave of damper'd notes in the treble, playing the note will make two 
dampers rise, which then proceed to stick, falling slowly when the note 
is released.  One thing I noticed was that the whole action was about 
2mm from the front of the keybed, and when I pulled it back out so it 
meets the keyslip, the damper sticking problem was solved.  My guess is 
that the keystick in the back is pushing up a few damper levers, and 
catching the side of its neighbor's lever.
Another problem is that the keyboard shift happens a little diagonally, 
and the action might be creeping its way backward over a few days of 
shift, so the problem with sticking dampers has shown up again.
Dampers all seem fine, no friction issues.
Any hints would be appreciated,
Richard Barber
Santa Clara Valley, CA