Thanks to all again for the continuing discussion of Duo-Art regulation.

After all the input I received, from fellow MMDers, and noodling over
it for a week, I finally determined the problem was me, not the piano.
I had been trying to make the thing play softer, but I don't think
that's in the cards.

The springs I had put in were way too weak, and that in itself
prevented me from even setting the zero level properly.  The springs
determine the slope of the vacuum curve and I handicapped myself right
out of the chute.  I used up a third of the regulator travel just
setting the zero, and then had a flat vacuum curve.

So I put the original springs back in, and set it up per procedure.
I now get a pretty good curve.  I get 30" accompaniment max, and 42"
theme max, 60" at crash.  I can get more accompaniment, but the curve
gets pretty steep at the low end.  The way I left it was a compromise.
The accompaniment play/no play test is pretty good, and I get 30".

By the way, the theme side does much better on the play/no play test,
even though the curve is steeper.  I found the original springs to be
a bit different.  "Original" is a relative term here, as in this case
it only means the springs that were on the piano when I got it.  One
spring was .048" wire, the other was .052 wire.  I put the .052 spring
on the theme side, as that side is supposed to get the stronger spring.

Perhaps the accompaniment needs a stronger spring so the curves follow
better?  I dunno, but I'm pretty happy with the way it plays now.
In any event, the stack and the expression box and the accordion
pneumatics all appear to be good and functioning correctly.  If nothing
else, I've added to the old "how it's supposed to work" databank.

A couple of old adages come to mind here:  "We get too soon old and
too late smart," and "Don't fix it if it ain't broke."

I appreciate your expertise on the subject.  This is a great resource.

Ray Fairfield