Piece of cake.  Take a plastic garbage bag, and make a strip wide
enough to cover the bottom 3 holes of the tracker bar, and one wide
enough to cover the top 4 holes.  Tape these to the spool box such that
you can flip them down to cover the holes when playing Ampico/Duo-Art
rolls, and up out of the way when playing 88n rolls.  The thinness of
the garbage bad plastic is such that you won't have air bleeding
between the roll and the strip causing false notes to sound.

Karl Ellison
Ashland, MA