Maybe try setting the "term power to SCSI bus" jumper. I know I have lots of Seagate drives, and that's usually an option that I choose.

I'm pretty sure that you can still get the manuals from Seagate - they're the only other hard drive company that still keeps stuff for virtually every hard drive they've ever made. Maybe they don't keep docs for 14" or even 8" drives, but I know first hand that they've got specs for 5.25" and 3.5" drives from at least 1988.