In latest UMPIO gig I saw 2 weeks ago in Turku/Finland, there was this amusing moment, where he noticed that one of the source sound tapes didn't work. So he just took the tape from deck, pulled out loooong piece of tape, and started rewind in back into tape with his finger. Many though this was some sort of performance act, but all it was, was to get tape working again. And it did. Still very nice moment, despite it of course had no instant impact on sound. Visually nice, to see tape treated boldly in very physical manner. Not exactly damaging it, but also perhaps not being too cautious what if it gets damaged.
Set all in all, was great mix of contact mics and junk, electronics, kaoz pad (!!!), pre-recorded tapes... resulting less of noise, more electro-acoustic type of sound.
One has to remember that tape, is most of all magnetic information. I don't think all the same things (sandpaper, melting etc) as works for turntable noise. Still, there is plenty of possibilities. My favorite is simply to see what comes from using something which is not new. Most of walkmen are somehow slightly defect. From combination of somehow slightly worn or used tape & slightly malfunctioning playback devise, results the details in sound what one couldn't perhaps "compose" or plan. Only to find.