I'd be real careful running them on a "fast" drive. I just tried to
archive about 120 TK50s and almost half of them stuck to the head
because of the coating coming off and gumming up the head.
--
I had exactly the same experience a few months ago. The formulation
of TK50s appear to 'shed', dumping residue when the tape reverses.
If you are going to try it again, find a drive where you can easily
access the head, so that you can clean it before EVERY attempt to
read a tape.