-- non-subscriber, please reply to sender and MMD --

I have seen both [motor] speeds used, the slower speed on the older
instruments.  The pulley on the faster motor shaft is smaller, so that
either motor will run the pump at the recommended speed of approximately
90 RPM.  These motors were made by the Electric Specialty Co. of
Stamford, CT.  They also made similar-looking DC generators for pipe
organs, run from a pulley attached to the blower shaft.

Good luck!  (If you need to have the double pulley made, I can supply
the correct diameter.)

Jeffrey R. Wood