This subject of the alignment of the Ampico B tracker bar expression
holes is explained in detail in Larry Given's book, "Re-Enacting the
Artist".  Copyrighted in 1970, this book is now out of print, but many
libraries have copies.

Pages 52 and 58 explain how the holes, offset by 1/32 inch, compensate
for the differences in speed of the expression regulators of the two
Ampico systems, A and B.  The offset was an effort to make the A coded
rolls play correctly on the new faster acting B expression system.

When the new B rolls were punched, this offset was taken into
consideration for proper placement of roll expression holes.   This
clever design made A rolls somewhat compatible, but still not 100
percent, with the new B piano.  More importantly, the new B rolls were
100 percent backward compatible regarding expression timing on the
thousands of existing Ampico A pianos.

Bob Taylor