Barry,  Take a look at the pictures at the link below and see if this
is similar to what you have.  Also, are there paper edge sensing holes
in your tracker bar?  Again see pictures at the link below.

http://www.geocities.com/Heartland/Ranch/9374/stroud/stindex.html

I have a few more comments, but I'm afraid you are referring to the
grand piano spoolbox and my comments would be based on the upright
version.

Sam Harris - Player Piano Restorations Illustrated
http://www.geocities.com/anneharris1/