Hi Sam, I am making a lot of guesses here but I hope it will help.
> 15. When the pneumatic feed channel is blocked with my finger I can
> feel the valve turn on, but when I remove my finger the valve shuts
> off again.
Sam, it really sounds like the inner valve material is too flexible.
When you remove your finger and the suction shuts off, you are causing
a rush of atmosphere down the pneumatic feed hole. The flexible inner
valve is responding just like a pouch would.
> 14. Some valves screech.
When I was a kid, I could put a blade of grass between my thumbs and
blow through it and make a pretty loud screech. I suspect the same phe-
nomenon is happening with those inner facings. This is just a guess.
The reason you are not having trouble with the outer valves is because
they have a heavy backing plate, and they only seat when the note is "on".
I am assuming the valves are like a Standard in this case. Standard
inner secondary valves depend upon the material being fairly stiff.
The backing plates help, but the material cannot be so flexible for the
edge if it is to "roll" in either direction. In most cases, the front
plate is smaller so it will be able to roll toward the valve seat.
This could easily cancel out the 1/16" travel you have in the valves.
Consider this for a moment: When the note is "on" the pouch is trying
to push the valve toward the outer seat. The suction in the valve
chest at the same time is also drawing the valve in the opposite
direction that the pouch is trying to push it. Even when the pouch
overcomes the balance, and pushes the stem forward, your valve is
flexing and 'hugging' the seat, compensating for what valve travel you
have set. The valve becomes confused and does not know what to do.
(Like me sometimes ;-)
If you are absolutely determined to use that material, you are going
to have to glue it on a fibre backing plate so it can not roll, and
install it for the suction side. You will not need the original
backing plates in this case. Just make sure that it can wobble between
the collars and the travel is correct, and all should be well.
I hope this helps. By the way, we missed you in the chat room
Andy & Chris Taylor, Tempola Music Rolls