Hello Ian,  You might try powering the switch shut-off pneumatic from
regulated suction.  I know you're not supposed to but, if everything
is tight, it shouldn't really matter.  The vacuum will then be cut off
from the pneumatic during rewind by the action cutout.  Haven't tried
it, but in theory... ?

Good luck!

Jim Heyworth,
Sechelt, B.C., Canada

 [ See also the Ampico B "Rewind and Repeat System" shown
 [ at  http://mmd.foxtail.com/Tech/Ampico/index.html
 [ -- Robbie