I've got a really busy three days ahead (AMICA's San Francisco
Chapter's due to visit here), so I can't go into it a lot of detail
just now, but on p. 352-353 of the December 2008 AMICA Bulletin (v.45,
no. 6), I have pictures of my transposing tracker bar, with a picture
of what sounds like the one you have at the bottom of p. 353.

Mine is set up to move the roll to the left about 1/4 to 3/5 inches to
the right on play [this sentence seems unclear.  Relief Editor].  This
requires the left spool end to be pulled out  about 1/2" or it will
tear on reroll.  However set up like this, the paper never touches the
spools on reroll.  I like it so much I have it on both my Steinways.

I also put some shims on the takeup spool to widen it about 1/8".  This
is for the sake of old paper rolls. I am cheerfully able to play even
my Audiographics.

I replaced the ear-adjustment screw with a new brass screw, of which I
ground the top flat, and turned it into an arrow.  The inside end I
ground ovate so that in 1/2 turn the ear moves all the way in or out.
This way I can set the tracker to track any roll perfectly at the touch
of my fingers.  My system is much better than the ear system of either
the Ampico or the standard Duo-Art.  There is a picture of this on p.
352.

Tockhwock