Thank you for your responses.

I have just ordered a Vacuum Gauge.  I haven't needed one until now.

SLOWING DOWN PUMP MORE: This weekend I found a pulley that was made for
a larger belt width and tried it. It made a large difference in the
pump motor speed.  The RPM on the pump went from 90 RPM down to 70 RPM.
The piano has problems playing properly without making other
adjustments but when I Manually hold the spill valve up on the
expression box it plays fine. I don't intend to run the piano with this
pulley because the Auto Replay function doesn't work properly because
of the sluggish delay seen when the hole is opened on the bottom
take-up spool. The auto shutoff also has problems.  This may be another
problem but I will have to see what the vacuum gauge reads when I get
it.

The pulley that originally came with the piano was 2".  The pump ran at
102 RPM with this pulley. I did find an old Duo-Art service manual from
1927 that states that the RPM value on the pump should be 120 to 125
RPM just as Spencer stated. I have noticed a slight lag problem and the
piano running out of air on one spot when playing "American in Paris"
when using the pulley that runs at 90 RPM.

Another affect that I noticed was that the spill valve had a greater
affect on the playing volume when the pump was operating at a lower
vacuum level than at the higher level.  This may be because more
percentage of the total air is being lost thru the spill.

At this point I know:

1) That the 2 springs are original with correct tension.  I have
compared it to a 2nd regulator. The Theme regulator has the stronger
spring.

2) Leakage because of using the Cross valves may be a problem.  I
didn't touch these valves when I changed the pneumatics.  I will
check this using the procedure described by Craid B. when I get my
vacuum gauge.

3) The accordion closures are working properly when viewed at the
regulator. No funny tubing errors.

Note: One thing new that I have noticed while viewing the regulator
while on the floor is that the exponential loudness problem is
happening when the accompaniment accordion is closing all the way. The
more I think about this, I may just have a problem where the
accompaniment volume is greater than the Theme when playing loud and
they cross at bad points. I started looking at the Accompaniment holes
in the roll and saw this correlation for the first time. I reduced the
travel distance for the accompaniment and the exponential loudness
problem has gone away.  Where is that vacuum gauge!

4) The theme valves seem to switch OFF properly.  When manually
increasing the theme volume from the front panel, the keys that are
played with expression are played very loudly.  All others play at
the lower accompaniment (background) level.

5) The Room that the piano is in has wall to wall carpet.  The hammers
may be hard but I don't think they need immediate work at this
time.  At some point I need to remove the keybed for the first time
and fix other problems such as hammer knuckle cleaning, increase the
travel of a few of the bass dampers and will try things like water
and Alcohol on the hammers to soften the felt striking area as
suggested by Larry Fisher.  I like the player action work more than
the piano side of this hobby.  It seems that I'm doing more piano
work like sound board repair, string, pin and hammer replacement.

At this point I am going to start looking into the spill valve
adjustment and Mufler Felt hole as talked about by Spencer C. and Craig
B. I did make a small change to it (but don't remember when) that
increased the opening when playing at low volumes.  My thinking was
probably wrong when I did this change.   I thought that letting more
air in at low volume would also let more air in at the loud volume.  In
reading information that was received from FOXTAIL I think that I may
have caused a problem. I forgot to mention this in the original
document.

I may be letting in too much air into the spill value when playing at
the softer volumes.  This may be causing me to set the 0 adjust to a
higher value than necessary.  When the accordion pneumatics close down,
the air in the spill is also closing which pulls even more air thru the
regulator. This should be a fairly easy change to make and see how the
loudness problem is affected.

The small service manual does mention "OPERATION OF THE ATMOSPHERE
INTAKE OR SPILL".  It says to adjust this valve to close off completely
when power #10 is required by either accordion pneumatics.