> tape broke and got tangled up and likely ruined

I'm far from a beard-and-suspenders type who got to use those systems when they were current, but my understanding is that When a tape tangles it doesn't affect the magnetic data stored on the tape: only a sufficiently powerful magnet can do that - even if it got tangled-up inside the tape machine one would hope the machine was designed to not energize the erase or write heads unless the tape was known to be moving smoothly through the tape transport.