With reference to Art Reblitz's suggestion about warping affecting the
free operation of transmission parts, certainly I intended no criticism;
I hope no one else heard any!

It's too bad that some folks with useful information respond directly
to the author rather than responding to the MMD.  I've gotten a nice
note from a fellow from Down Under who states that a dandy test of an
air motor can be done by blocking the vacuum connection and turning it
in reverse.  If pneumatics and valves are tight, it won't turn without
great resistance.

Mine turns with very little resistance so it would seem that remediation
is in order.  That's what 'due for a rebuild' means after 40 years.

I did not put a vacuum gauge on the governor output; there certainly is
not much oomph there.  I still have not heard what's inside the governor;
I'd expect that there is some control associated with the pneumatic so
that uniform vacuum is applied to the tempo slide.

Douglas S. Heckrotte
Philadelphia, Pennsylvania