We are going over an Operators Piano Co. Coinola Midget and have the
pump opened up.  It is a four 'cylinder' pump in the square box style.
It furnishes vacuum for the piano stack and pressure for the pipes.

The output of the pressure side seems a little low, and upon examination
there seem to be no stiffeners in the pump sections.  I know pressure
pumps always have stiffeners, and vacuum pumps normally don't.

It seems to me this one should have stiffeners since it is providing
pressure.  Is this correct, and if so can I get away with adding
external stiffeners or do I have to remove the motor cloth and put the
stiffeners inside as they are on a pressure pump?

Scotty Greene - DeBence Museum