Scott,  First, make sure that the pump cutoff valve is connected and
functioning properly.  This varied quite a bit in design and placement
in early Duo-Arts, but basically it is a large valve that cuts off the
main vacuum to the stack during rewind.  In later Duo-Art grands it is
in the "modulator" box between the pump and the expression box.

Assuming that is okay, it is very common for Duo-Art grands to play
poorly after moving, with the symptoms you describe.  The most common
cause is tipping the piano on its side and the vibration of moving
rattle the 88 valve spools in the stack and some of them have shifted
position or rotated so they do not form an airtight seal with their
lower valve seats after the piano is tipped back on its legs.  This
substantially increases the total stack leak into the system, giving
the symptoms you describe.

This is may be a more common problem with cross-valve seats and
synthetic foam rubber replacement valve facings, but it can also occur
with the later round seats or with leather facings on either type of
seat, especially if the leather has become embossed or has stiffened
with age.

The quick fix is to supply as much vacuum to the stack as possible,
ideally about 30 inches water-gage or so, and quickly cycle each
note valve in the stack multiple times, including the four extreme
"non-Duo-Art" notes at the treble and bass ends.  Sometimes this can
be done by switching "Duo-Art OFF", manually moving levers to the
loudest Accompaniment setting (and possibly the loudest Theme setting
as well) and then running a test roll section several times that
repeats all 88-notes quickly.

Sometimes a stronger external vacuum source than the pump may help.
This will usually rattle the valve buttons back into place somewhat,
sweep out any dirt crumbs that may be keeping valves from seating, and
the strong vacuum will begin embossing the valve facings in their new
positions so they seal better.

After this treatment and a few days of playing, you may also want to
do a fine readjustment of the "zero" level knife valve settings of the
expression box.

The long term fix for this problem is usually a full stack rebuild,
with properly supple, new brushed leather valve facings that seal more
reliably and that are not as affected by their exact positioning.

Best regards,
Ralph Nielsen
http://www.historicpianos.com/