I have finished a complete rebuild of the Duo-Art grand expression
box and I am having a difficult time getting the Theme Zero Setting
soft enough.  The Accompaniment side works perfectly and can be
adjusted so soft to the point that the piano does not play.  The
dynamics are perfect as it goes through the test roll.

However, I cannot get the Theme side to soften anymore than what
I would call moderate.  I've adjusted the knife shaft/control arm
to softest (fully closed) position but the piano (Theme notes only)
continues playing fairly loud during the Theme Zero Setting procedure.

There is some expression as the Theme accordion stack is closed but
since it starts so loud, it's not that dramatic.  The crash valve works
perfectly.  The Theme expression does switch on and off to the treble
and bass when it's supposed to, so the box is correctly reading the
"snake bite" holes.

When I bench-tested the unit, virtually no vacuum was seen at the two
inlets on the expression box when I adjusted the Theme control arm to
minimum (fully closed).  But when hooked up to the piano, I still get
fairly high vacuum.  Yes, the accordion stack is working properly.
The control arm does return to rest (softest) setting when the
accordion stack is not activated.

I'm hoping someone out there with more experience that I can help me
troubleshoot this.  The box itself seems to be working properly and
switching from accompaniment to theme as marked.  If I manually suck
and blow into the two inlets, you can feel the internal valve seats
open and close properly.  I hate to take the box apart again if not
needed.  Please call (940-642-0155) or email me if you've got any
ideas.

Jim Quashnock