Hi All,  Well, I must say Beth Ann has me scratching my head on this
one.

Typically, the by-pass flap valve, which is build into the supply
flange on the top of the vacuum pump (actually mounted directly
underneath the flange), closes off the pump so that vacuum can not leak
'back' through the pump when the foot treadles are used.

Conversely, when the electric pump is used, the vacuum from the pump
'sucks' the flap valve open allowing the air to be sucked from the
lower section.  My point is that it sounds like there is a problem with
the flap valve in the vacuum pump.

What throws me about this question is the mention of an 'electric
valve'.  The only units I know of that use anything similar to an
electric valve are the Universal, Baldwin, Wurlitzer and Story & Clark
type players with the electric roll motor.  They have a vacuum sensing
switch which senses that the foot treadles are being used and then
turns on the circuitry for the electric motor.

However, if her friend is able to "put a piece of cardboard over the
valve so she can pump it", I have to assume (I hate that word) she is
also disconnecting the supply hose at the pump.  If that is indeed the
case then the problem is the flap valve in the vacuum pump.

The flap valve is a very simple device that can become disconnected
since it is only held in place by a piece of tape which acts as the
hinge for the 'flap'.  This flap can be easily tested by sucking on the
supply flange.  It should close immediately upon sucking.  If it does
not, simply remove the three screws that hold the flange to the pump
and look to see if the flap is correctly affixed.  If not, get a piece
of strong tape (like reinforced packing tape) and put on a new piece of
tape, then reassemble.  The problem should be solved.

Also, the other units mentioned above also use a flap valve at the
vacuum pump.  However, it is mounted on the underside of the vacuum
pump, is a little more difficult to access and uses a rubber flap which
is held in place by two plastic pins and a retainer.

Musically,
John A. Tuttle