Gerry Bay commented that there is a tracking problem with a Duo-Art.
While it does sound like there isn't too much he can do for just a few
rolls that don't track, I have found that one can add a little more
tracking power to accommodate wide and narrow rolls by replacing the
tracking finger pads with a heavier, longer pile leather suede. It can
make a big difference.
Naturally, he will then have to reset his tracker ears. If everything
else in the system is centered, however -- like the cam at its extremes
when the tracking pneumatic is at its extremes, and the take-up spool is
centered, then after the pads are replaced with deeper and softer pile
suede (heavy cabretta is great for this), the tracking will be a bit
slower acting (not to notice) but will be much more lenient because you
will be able to set it to respond to narrow rolls, whereas before, it
wasn't cheerful about them.
I suspect that the few rolls that don't track well are probably too
narrow, but it's hard to say without actually being there. This trick
will give him more latitude. As the pads are drying with plastic
glue, press them hard into the tubes they seal and make a deep
impression. Then begin with your best tracking rolls first and
graduate to your worst ones. You will find out how to "split the
differences" in such a way that it doesn't really affect the good
rolls, but helps the ones that you're not tracking very well.
If, when rerolling a roll however, you see that it tends to crawl up
one roll flange or the other, that means the finger on that side of the
roll is crowding the roll. Either that, or you have to readjust and
tighten up your tracking system all the way around, like for example,
the brackets holding the tracker pneumatic are loose or springing back.
There should be three of them. Sometimes the rear bracket screw is
loose or stripped. Any kind of play will cause this.
[ I believe my Themodist Pianola has the same tracking system. After
[ replacing the pads on the tracker ears I noted the same improvement
[ which Craig describes. Occasionally I play a roll with a bad or
[ improper right-hand flange, and the tracking mechanism moves to the
[ limit of the pneumatic. When that happens I temporarily re-adjust
[ the turnbuckle link which connects the pneumatics to the cam, so
[ that the pneumatics and the music roll are simultaneously centered.
[ -- Robbie