Northstar Assistance Request

Greetings, I pulled the Northstar Horizon out of storage now that I have time to take another crack at restoring it. It has an MDS-A3 controller, which I connected to an MPI-52 full-height 5.25" drive. When I boot it, I can hear it jiggle the heads a few times (a good sign generally) but then it just spins the disk for a minute (I can't hear the heads moving) and then stops. I've used disks in it sent to be my Doug Coward and by Don Maslin (Don, I put some money in an envelope to mail to you on monday!) and both exhibit the same behavior. Are there any reasons I shouldn't use an MPI-52 with the MDS-A3? Could the jumpers on the MPI-52 be set incorrectly to act as a single drive in this system? What other sorts of problems will cause this sort of behavior on this particular machine? At no point is anything displayed on the terminal. I've verified the baud rate at 9600 and tried with hardware handshaking on and off. I've also tried both serial ports as an experiment. At any rate, I don't think serial comm is the problem here since it's my understanding that the N* will only display terminal messages IF it successfully loads an OS and I just don't hear those heads moving around doing reads. In either case, I ASSUME that the terminal needs to be plugged into the RIGHT serial connector, closest to the parallel ports. I put a breakout box on it and it says all the lines are happy. Thoughts? Suggestions? Ideas? Speculations? Thanks... Anthony Clifton