I've been working on a "modern" (1978) Standard player system.  It has
the suction box with the die-cast top with four valves on it.  I can't
seem to get it to put out more than 18" water gauge vacuum.

My little test box, which is nothing more than a simple vacuum box,
can easily do 30" on this piano, and up to 50" if not a lot of notes
are playing.  Any suggestions out there?

I shortened the choke pallet, so it can open more, and I cut 1/8" from
the exhaust slot to reduce back pressure, but that only got me from
16" to 18."  If I slide the Tempo lever to "0" I can get 20".

Frankly, I'm buffaloed!  I'm thinking maybe I should get a new vacuum
motor unit -- and if so, any suggestions?

David Dewey
Oroville, California