I've had some success, many years ago, repairing 8-track tapes.  The
tape is standard 1/4" tape with one difference: the tape backing is
coated with a dry lubricant so as to make it slide easily in the coil.

It will probably be necessary to open up the cassette, observing the
location of components as you do.  I've used ordinary audio tape repair
tape to make the repair.  Splice it as you would any 1/4" audio tape.
Don't use the tape which is for repairing audio cassettes as it is too
narrow.

Jim Cook