All of the pump motors I've seen in grand pianos were 6-pole motors,
therefore they turned at a bit less than 1200 rpm on 60-Hz power,
or 1000 rpm on 50-Hz power.  The same motor could be used on either
50 or 60 Hz, but a larger motor pulley was installed for the lower
mains frequency to compensate the slower speed.  I think the Ampico
and DuoArt motors were rated for 1/6 horsepower.

These motors were designed for these special needs:

1. Operation with the rotor shaft vertical and the pulley at the
bottom, which requires a good thrust bearing on the bottom end bell.

2. Quiet running, with low hum level.  The magnetic design was quite
conservative, meaning that the flux density in the steel didn't
approach saturation.  That's why a piano motor usually bears a
horsepower rating of perhaps half as much as a modern industrial
motor of the same case size (and often runs quite hot).

To reduce the cost of fractional-horsepower motors most are
designed to start without an external starting capacitor; this
type is called "split phase". The "capacitor start" design is
more expensive but has much greater starting torque (which isn't
needed in a piano).

All the designs allow swapping the starting winding wires in order
to start the motor in the opposite direction.  The centrifugal
starting switch opens the circuit to the starting winding as the
rotor approaches running speed.

Often the motor burns up simply because the connection to the
starting winding is bad, perhaps due to a loose or corroded
terminal screw, or due to failure of the starting switch. When the
motor power is applied without a functioning starting winding, the
rotor has no torque at all, and just sits there humming.  In less
than a minute the main winding will overheat and smoke, unless the
motor is protected with a simple thermal time-delay circuit breaker.

I'm not surprised at the $300 quote you got to re-wind the motor.
I can imagine that it would take the motor repairman about one day
to clean out the burned windings, build the winding fixture, wind
the new coils, and fit them into the stator slots.  And _then_
he must carefully drive wedges into the slots to prevent excessive
hum and buzzing.  It's a real craft.

Hopefully someone in this group has a serviceable old pump motor you
can obtain. Have your local motor-man clean and lubricate it and
check the starting switch and wiring before it's installed in the
piano.

If you wish to experiment with a modern substitute try a single-
phase 1150-rpm fan motor rated for 208-volt service.  It should run
quietly and nicely on 115-volts.  A motor rated for 115-volt mains
may hum too much.

-- Robbie Rhodes