I apologize that I have not kept you up to date. Since mid February, Quantum has replaced the drive, and we still got errors that traslated to the picker or tapes. Then they replaced the chassis and we still got picker and tape errors. They replaced the chassis again and this time we bought 15 Quantum tapes and re-used our cleaning tape - still got picker and tape errors. They replaced the drive again, and now we seem to be running backups again! (Yay!!!!) We have Veritas errors on certain tapes, but we've done a quick erase on them and it seems to be going well so far. We still don't have a full week of backups, but tomorrow will make one week.
If we get any more tape errors, I'm going to have Quantum replace the tape in question (they will only replace Quantum brand tapes).
Also, we're using an HP SCSI Ultra 320 card that does not support an array controller or RAID. I honestly feel our problems have come to an end and it was a defective quantum unit (or our original brand new tapes suddenly went bad).