I have noticed tracking irregularities in some Duo-Art players,
mainly because of leakage in the tracker pneumatics.  If one leaks,
even slightly, it will move the roll toward the stronger side.  The
leaks are usually found in the glued hinge end, or sometimes the
bellows cloth has failed.

Test for leaks.  Remove the tracker pneumatics from the piano.  Attach
a hose to main supply nipple on the tracker pneumatics and place a
short piece of hose between the two nipples that go to the tracker bar,
sealing them off.  Next, gently blow into the main supply to inflate
the pneumatics and immerse the entire unit (a few seconds) in a pan of
water.  Bubbles will be evident if there are any leaks.  Since the rubber
cloth is supposedly waterproof, and the wood is painted, a quick dip in
water will not harm it, if it is quickly dried with a towel after this
test has been performed.

To lessen the possibility of shredding rolls, the take-up spool must be
free of sluggishness from the take-up spool brake.  The more loose and
free the take-up spool is, the less chance for tearing rolls on rewind.

Test your take up spool.  With the lever set at rewind, can you spin
the take-up spool, or does it tend to stick and be slow?  If so, this
is one of the problems.  Be sure the bearings of the take-up spool are
clean and lightly oiled.  (I use a drop of Singer Sewing Machine oil.)

If the rolls still persist in shredding on rewind, it might indicate
the roll has reached the point of no return, and it is time to search
for a replacement.  Some rolls have been rewound unevenly and stored
for many years.  Because of this, the paper develops a memory of being
in the wrong position (side-to-side and uneven) and keeps wanting to
return to it.  This unfortunate condition is not likely reversible.

Bruce Clark