Re John W. Miller's request in MMD 010919 -- this inquiry will
probably draw tons of responses!  Everybody has their own favorite
methods.  Here are my two:

1.  Total manual control by the piano operator.  Most rolls in a
decently set up spool box track just fine without assistance.  For
old rolls, this approach is the gentlest, safest  and least harmful
to roll edges.  This assumes the operator is paying attention!

2.  Holes in the tracker bar (Standard Action) -- Once correctly
adjusted and kept clean, this system does a good job of tracking
without damaging edges.  It is not effective when playing rolls with
previous unrepaired edge damage.

Next?

Ed Sprankle