We had a similiar problem a few years ago. Very old tapes can go
bad (the oxide coating starts to flake off, resulting in dropouts)
but in my experience the problem is most likely in the drive itself.
First off all, make sure that both the tape head and the BOT/EOT
senson are clean (a cotton swab and isopropyl alcohol are good for
cleaning purposes; swab in the direction that the tape runs). The
other problem we have experienced is that the tape head becomes
magnetizied with time ( not too suprizing in a NMR lab!). Use
of a tape head demagnitizer will help here (remove the tape from
the drive first!).
Failing these measures, perhaps your computer department still has an
old drive sitting around........
Cheers, Deane D McIntyre
dmcintyr@acs.ucalgary.ca
Bio-NMR facility
Dept. Biological Sciences
University of Calgary