Thank for all the helpful comments and replies.  I guess I did not
do a very good job defining the reason for my original question.
The Coinola in question has been operating well for some time.  It
uses a box pump originally providing both vacuum and pressure, but
recently it showed signs of inadequate flow or pressure to the pipes.

I know these are different problems; both the vacuum and pressure
seemed low.  The vacuum side of the pump was replaced with a blower
before I ever saw the machine.  So I tore down the pump.  It is
definitely not untouched original, but the rebuild job looked of high
quality.  No discernable problems, but no stiffeners.  That's why
I asked the original question.

The problem turned out to be that the inlet where the original pump
sourced vacuum for the piano action had an elbow in it that was pushed
in so far it restricted the inlet.  That may not be my only problem,
but if you don't let the air in you can't get it out!

Again, thanks for all the information.  You always learn when working
on a problem.

Scotty Greene - DeBence Museum