Hello,  In spite of their high price at the time, I bought a few of the
"Green Plugs" for various reasons.  They were supposed to be active
power factor controllers, which is a good idea, but I think the design
was not good as this sort of thing really needs to be carefully matched
to the requirements of the motor.

I bought one for my antique refrigerator thinking that it would lessen
the starting strain on the 75-year-old compressor and also make it
quieter and run cooler.  It did help with the noise aspect a little,
but it was also one of the first things to fry from a power surge.
I don't think I would ever put one on a rare piano motor for the
reasons that Craig mentions.

Most piano motors that run hot do so because they are overloaded by
incorrectly adjusted spill valves or other causes such as motor pulleys
that are too large.  I have been very concerned about motor overheating
because I sell a device which allow the piano to be run for many hours
at a time since no rolls have to be changed.  I caution customers about
overheating and recommend the use of a thermal safety device if there
is any chance that the motor is running hot.

Remember that these player piano motors use class A cotton covered
wire.  I forget the temperature rating but it is very low compared to
modern motors.  Although it is expensive to rewind motors, it is the
best insurance against a burned piano and or house.

My preference is for a remote pump.  You can keep your antique motor
for posterity and use a modern noisy one in a remote location and not
worry about a fire.

Best regards,
Spencer Chase