Hi All,  I believe there are at least five types of tracking systems:

  single hole
  double hole
  four hole
  single ear
  double ear

There is also a system that employs 'collapsing flanges' on the take-up
spool.  As the spool turns, the flanges move inward until they touch
the paper, keeping it aligned in the center of the spool.

However, I'd like to address a common problem with old rolls that
ultimately contributes to tracking problems.

When the left flange of the roll gets loose with age, the spring-loaded
chuck on the left wall of the spoolbox can easily push the flange into
the left edge of the paper, causing the paper to curl slightly.  During
rewind, as the paper tries to squeeze in between the flanges, either the
paper edges get curled or the roll rips.

This problem is easily solved by removing the left flange (on the roll)
and putting one wind of Scotch tape around the area where the flange
goes into the cardboard spool.  When you push the flange in, leave a
small amount of free air space between the flange and the paper
(1/16").  This allows for normal expansion of the paper during the
humid times of the year.  It also helps insure that the paper will not
be damaged during rewind.

Musically,

John A. Tuttle