The drive is made my Quantum with a change to the outside and firmware as per Dell standards. So it is perfectly normal for it to show up as Quantum.
Spend the money for a new Quantum or Maxell tape and see how it works. Chances are there is a problem with those tapes.
I also recommend getting a copy of StorageCare Sage xTalk Management Console
http://cp-quantum.talismaonline.com/display/2n/articleDirect/index.asp?aid=1306&r=0.7547571With it you can run diagnostics on the drive.