Exabyte Mammoth M2 Tape Drive Not Recognized

[homeboy4]

I have a PC running WinXP Pro with SCSI RAID, separate SCSI boot disk and third SCSI card (Adaptec 29160) for an Exabyte Mammoth M2 LVD external tape drive. I have Retrospect to operate the tape. I bought all this stuff a few years ago. I try to make it work and can't, then forget about it in the pressure of other work. Then try again months later. Most recently a tech came and took the computer away because the computer couldn't see the tape drive. He said it was a bad cable. He brought the computer back with a new cable and I saw it recognize the tape. Then I had some problems with the software and quit dealing with it. Months passed. I finally got around to upgrading to the latest version of Retrospect. Armed with the upgrade, Retrospect didn't see the tape drive, then it did, but it wouldn't backup because of a tape drive error. Exabyte said the error could be corrected with a firmware update. But now the computer doesn't see the tape drive again. I did all the usual stuff: wiggled the cables, took them off and put them back, changed to a different SCSI ID number. I tried the old cable that supposedly didn't work. I have the latest 29160 driver. And, yes, I have a terminator. Although the computer doesn't recognize the drive, it will sometime pause at the tape's ID number as if it is going to recognize it, then it moves on. It doesn't pause at any other numbers. Then sometimes it will scan without pauing but skip the tape's ID number. Which one it does depend on whether I have rebooted the computer or done a cold start -- I think. In any case it doesn't recognize the tape.

So is it the SCSI card? Probably not, right? Is it the cable? Probably not, because it pauses so it sees "something." Could the drive be defective? According to Exabyte, from what they can tell over the phone, it appears to be working normally.

I'm out of ideas.