>After running the restore vol it fails due to media read error on one of the
>volumes.
...

It's rather unlikely that so many tapes are bad: maybe it's your tape drives.
There have been recent discussions of microcode levels... In general, evolved
drive microcode levels tend to sequence operations better and handle tape
motion better, as well as improving tape error handling.  Given the severity
of your problems, I'd recommend having your CE look at the problem.

  Richard Sims, BU