I have a small Aeolian-London Pianola Duo-Art with only 85 notes.
The tracker bar has a transpose lever that moves two semitones plus or
minus.  The tracking is done by four holes in the tracker bar rather
than the normal fingers that feel the paper when it wanders too far
left or right.

From the front, it looks like any Duo-Art tracker bar but from the
back, it's completely different.  There is a brass bar that supports
all of the hose nipples for the 80 playing notes.  This can move left
or right by two holes.  There are springs that hold this sliding bar
tight to the front brass portion of the tracker bar.  Very different
from anything that I have seen before.

Pete Knobloch
Tempe, Arizona