Thomas Henden writes:

> During a year period, my Duo-Art piano has been gradually playing
> more weakly.

Hi Thomas,  From your description, it is hard to tell what the problem
might be.  I suspect it had something to do with the re-regulator since
you didn't include this in your check list.

Take some masking tape and cover all of the playing holes on the tracker
bar.  You can do this as long as you don't keep the tape on the brass
tracker bar for any extended time.  Keep the expression holes open so
they are active.  You will have to cover the hole on the take-up spool
so the power switch will stay on.  Put the play-rewind lever into the
play mode.  Also put the player mode into the Duo-Art mode.

Now go under the piano and watch the two pneumatics on the Duo-Art
regulator.  When you apply power to the pump motor, these two pneumatics
should pull up hard.  From your description, they probably won't.
Check to see if the two accordion pneumatics are closed.  If they are
in their resting (open) position, your problem is probably in the
re-regulator area or the 88-note/Duo-Art mode switch isn't functioning
properly.

On the accordion valve box, remove one of the control hoses going to
the tracker bar and use your finger to turn the valve on and off.  As
you open and close the port on the valve box, you should notice the
accordion pneumatic moving. Only remove one hose at a time since it is
very easy to put the wrong hose on the wrong nipple.  Try this on the
largest bottom accordion valve since it is much easier to see the large
pneumatic open a close.  If it doesn't move or doesn't move the entire
distance, the problem is in the re-regulator area.

This re-regulator provides 4 main functions in the piano.   It supplies
regulated vacuum to the sustain pneumatic.  It supplies regulated
vacuum to the accordion valve block, and it supplies regulated vacuum
to the entire duo-art regulator when playing in the soft mode.  There
is also a bleed port that is opened when the player is put into the
rewind mode.

Check if the cloth on the regulator is in good condition.  With you
talking about the piano slowly playing weaker over time, it might be
that the cloth has ripped or is old and cracking internally between the
2 cloth surfaces.  Also check if hoses have come undone from any of
these re-regulator functions.  Having a major leak in this area will
reduce the vacuum level to where things won't work properly.

This is only a starting list of things to check.  I don't think it's
your expression box.

Pete Knobloch
Tempe, Arizona