>We have been receiving an abnormal amount of ANR8359E Media Fault, and
>ANR8830E Excessive media failures for volume.
>Hardware has replaced the cleaning brush, tape head, and card pack.
...
>Our CE said we are current on micro code for the library and drives.

Debbie - I'd say that your drive microcode is the problem, being
         hypersensitive about tape quality.  My understanding is
that this was a problem with the 3590 microcode that was around
when the 3590E was proliferating last year, but that newer microcode
was supposed to reduce the sensitivity.  In any case your CE is being
vague about what "current" is.  Do 'lscfg -vl rmt_' and look at the
"Device Specific.(FW)" value.  Compare with what is available at
ftp://service.boulder.ibm.com/storage/3590/code3590/.  Be aware that,
periodically, some levels of microcode are clunkers, and that either
upgrading or dropping back to get away from that level can fix
problems.

   Richard Sims, BU