Folks, my experience back in the 1960s, when I was restoring numerous
reproducing pianos, etc., was this: remember that the paper tracker
system only works on playing, not rewind.  I found numerous player
trackers did not work all that good and the paper did too much weaving
while playing.

I never was fond of the tracker-ears type system on the Duo-Art and
I discovered later that Duo-Art had gone to 4 holes in the tracker bar,
two holes on each end of the bar.  So I began drilling the tracker bars
with this 4-hole arrangement and with tiny pattern files squaring up
the holes, then sweat-soldering nipples at the back side of the tracker
bar for these new holes.

A little trick that worked good was to insert a small drill bit into
the hole and new nipple to hold it in place and also to prevent the new
solder from clogging up the new hole.  Solder would not stick at all to
the drill bit.

I will admit this modification takes a person with a good deal of skill
and aptitude and would not be for everybody to try.  You might wind up
spoiling your tracker bar.  Also we possessed spare tracker bars and
would keep one on hand, ready to go with this new modification.  Also
it would not be possible to do this job unless the tracker bar is
out of the piano so the new holes can be drilled with a drill press.

The excess weaving of the roll being played was almost totally
eliminated and rewind worked smoothly -- the faster, the better.

Ellsworth Johnson

 [ I've seen several old player pianos in which the tracking system
 [ was attempting to operate while rewinding, and was really making
 [ a mess of the roll!  I guess the tracker system shutoff valve wasn't
 [ working.  -- Robbie