Hi Ralph,

Now, here's the hard part. With the note valve in the 'off' position,
there should be "zero" air loss. So, the applied vacuum should
be identical the level when the device is hooked to the test jig.
This test is best done by mouth. Pinch the vacuum supply tube
going to the test jig and suck on tube (which you would otherwise
connect to the pump) until you read 7-10 inches of vacuum on
the gauge. Then put your tongue over the end of the tube, trapping
the vacuum in the hoses. (The gauge should remain steady.)
Now, release the pinched supply tube going to the jig. If the valve
and block are 100% air-tight, the gauge should only drop a small
amount (1-3 inches), and then stabilize. Most likely, this will not
happen because it's almost impossible for the valve and block to
be 100% air-tight.

Next, suck on the pump end of the hose again (valve still 'off') to
see (feel) how much air loss (or vacuum loss) you have in the
block. (Again, it should be air-tight.) Make a mental note of how
much loss you have by sucking on the tube until you run out of
breath. (Count the seconds.) Next, uncover the signal port that
goes to the pouch so that the valve activates. You can do this
two different ways. One, do it while you are sucking on the tube
so you can feel the valve change state. Two, uncover the port
first, then suck on the tube so you can feel how much air it takes
to collapse the bellow. Meanwhile, keep an eye on the vacuum
gauge and keep a mental note of the various readings during
the two tests.

Next, test another block and see how the results compare. With
any luck, the results will be very much the same from block to
block. If they aren't, you'll be able to start weeding out the good
blocks from the ones that need help.

Musically,

John