I have not seen the pictures of this piano, and I'm not going to claim
that I know more than Mr. Tuttle, but in my grandmother's player piano,
the vacuum box that she had added did not contain any type of valve to
allow manual pumping.  The result was that I could rewind rolls with a
tremendous amount of pumping, but there was no resistance at all, of
course because there was a 1" diameter hole in my reservoir.  All I did
was pull the hose to the vacuum box off and cover the nipple with tape
(until I can take it out and fix the hole correctly), and it worked
just great.

Michael Hamilton