I would say if it's happened with 3 separate DATs then it's highly likely the machine and not the media.
If you haven't cleaned it since you got it, give it a run-through with a dry-clean tape and a manual wet-cleaning.
Then, for kicks, I'd try an expendable DAT to see if the problem persists. If it does, it's the deck, and best bet is to send it in to Paul at
Pro Digital for repair.