Samuel Stroud asked about a problem with a centrifugal start switch.
Some of the more unusual centrifugal switches in old motors can indeed
be a difficult problem when they wear to the point of needing parts
replacement.  Repair is usually possible, but the cost can easily
become completely unreasonable.

If the instrument is not undergoing a full museum-quality restoration
where complete original condition is required, a solution can often
be found in the use of a solid-state centrifugal switch replacement.
These devices need no mechanical connection to the motor, and the
original switch is not used.  The replacement switch is most easily
mounted externally, but some motors have room to allow installation
inside the motor case to leave the external appearance unchanged.

I've used these devices on other (non piano) motors in the past with
success.  If I recall correctly, the brand name is "Sinpac" and about
10 to 15 years ago the price was about $40 or $50 for a model suitable
for a small motor.  I'm sure the cost is higher today.

Wayne Johnson

 [ See http://www.reliance.com/mtr/stearns/cat902.pdf 
 [ -- Robbie