In regard to the newer Aeolian shut-off switch: most of these
Aeolian players from the 1960s through the 80s have pneumatics
to shut off the electric motors, and most of these pneumatics are
dried out and rather useless at present.  I have done dozens of
service calls on these players and almost all have had this one
problem in common.

I have to take off the little bellows and recover it with fresh
rubber cloth to repair the problem.  This usually means two trips
to the offending piano but it has to be done.  If the pneumatic is
soft yet, but still leaky, you may use a light coating of silicon
on the rubber cloth to put a temporary fix on the problem.

Jim Jelinek - Player Piano Clinic