I ran a few experiments last night to try to answer some of my own
questions.

WHAT IS THE VACUUM READING AT THE KEY PNEUMATICS?  (Test #1)

This exercise was to satisfy my ignorance about where should I take my
vacuum measurements and if they were different near the valve section
in the stack.

On the stack there are 2 - 3/8 inch. hose fittings (1 for Bass and 1
for Treble) that are located on the bottom Tier.  These go to the bleed
assembly which contains individual bleed cups for each note on the
stack which is external from the stack.  This was the closest location
to the values that could be used.  All other thoughts means drilling
holes in the key pneumatic or stack which I don't want to do.

I disconnected 1 of these hoses from the stack and closed off the
opening going to the bleed assembly.  Leaving this open caused all the
valves to turn ON.  There is enough leakage in the pouches that closing
the hole is enough to turn OFF all of the values.

A hose was then connected to the 3/8 nipple on the stack along with the
vacuum gauge.  With the pump turned on and sitting at dynamic level #0,
the vacuum readings were measured.  Readings were taken on both sides
of the stack and at the elbow connections which were very close to the
Duo-Art regulator.

All of the measurements read 5.5 inches of water.  5.5" on the bottom
tier of at the Stack and 5.5" on the hoses near the Regulator.  This
indicated to me that I can take the vacuum readings at the regulator if
the stack doesn't have major leaks.

POUCH LEATHER LIFTING VALVES (Test #2)

In early correspondence, Spencer Chase or Craig Brougher talked about
tight pouch leather might be holding up 1 or more of the values in the
stack causing excess bleed problems (AMD 96.08.17).  With the vacuum
gauge connected to the 3/8 inch nipples on the stack, I ran a test roll
at a very slow speed so that I could watch the change in vacuum on the
gauge as each note was being tested.  The gauge had to be moved when
the notes switched to the other side of the stack.

As each note was played, the vacuum gauge dipped about 0.2 inches of
water. All of the notes on the stack dipped down. This is good since it
indicated that each valve was closing properly.

If any 1 of the keys showed no change or it went up in vacuum, then
this would have indicated the value was being held up above the valve
seat by the pouch, dirt, or even holes in the leather.

Note: I tried to do this test using the vacuum gauge close to the
regulator but was having a hard time reading the small change on my
gauge.

PRESSURE BUILD-UP IN MY DUO-ART REGULATOR (Test #3)

This test was to see how well my regulator knife blades are sealing
inside the regulator.  If they are warped and the stack relatively
tight, the vacuum numbers will creep up artificially high
(unregulated).

The regulator was disconnected from the stack (Both bass and Treble)
and both regulator ports were sealed with a vacuum gauge connected to 1
port and the pump turned ON.

What surprised me is that the vacuum reading showed 5.5 inches of
water. I could not get it to creep up.  I made sure that I didn't have
a small leak in one of the hoses or fittings.  The vacuum just didn't
want to build up. To help it along I manually closed the spill value on
the regulator. Vacuum didn't budge, still 5.5".  The pump and motor did
slow down just to a point where they stalled because of the added
load.  Playing with the accordion values would increase the vacuum but
it would slowly drift back down to the 5.5" 0 setting value over about
a 15 second period.

The Accompaniment regulator is working too good to believe, lets try
testing the Theme regulator.  Both Bass and Treble theme values were
opened allowing the theme regulator to kick in.  I can now see the
vacuum increase because of the build up.  It goes from 5" to 20" in
about 10 seconds and then stays at 20".  I placed aluminum foil over
one of the ports and poked a 3/32 inch hole in it and re-tested. The
vacuum level reads 6".  Closing and opening the hole allows the
regulator to "build up" pressure and always goes back to 6" when the
hole is opened.

I poked a 2nd - 3/32 inch hole in the aluminum foil and the vacuum
readings is still 6".  Playing with the Theme governor pneumatic
sometimes causes the readings to sticks at 5.5". This is due to the
Accompaniment regulator kicking in a 5.5".  Playing with the Theme
accordions always causes regulator to go back to 6 inches of water.

With the Theme valves open and at the 6" 0 setting, if I manually close
the spill valve, the vacuum level goes up to 6.2" and the motor stalls
if held down too far for too long. This increase in vacuum is probably
due to the small leak in the knife valve.

I don't think that I should go into the regulator to try to fix any of
the minor problems that I have seen. Vacuum Build Up is normal as far
as I understand and the sticking Theme regulator problem doesn't happen
if the Accordion pneumatics are used to change the vacuum.

RECONNECT STACK TO MEASURE ANY VACUUM DIFFERENCE  (Test #4)

Now that readings were taken without the stack, I reconnected it just
to see if the numbers would change.  No change.  The dummy bleeds (2 -
3/32 inch holes) and the stack still read 6.0" for the Theme and 5.5"
for the Accompaniment.

All this proves is that the regulator is working well or the stack
looks similar to the dummy bleeds punched in the aluminum foil.