The roll mechanism being in good order such as on types where the
sensing finger(s) move clear on "rewind", etc., then the rolls
themselves then are the problem.  If one spool end (opposite to drive
spool) becomes too slack in the core, the paper moves side to side on
rewind.  It is then put in its box and temperature and humidity effects
"take charge".

This roll may then not be played for a long time and it sets itself out
of alignment in the box, into the zigzag vertical pattern.  When you
try playing this roll again, more than likely it will tear.  It will be
hard to make good the roll again.

Try a new or in good condition roll to see the difference, hopefully
good.

Steve Bentley
Vancouver BC