troubleshooting an SA-400 disk drive

I have been monitoring this new problem for a few days. Actually, it first surfaced weeks ago, but I had zero time to look into it. Anyway, I have a three drive Smoke Signal Broadcasting disk system, in which one drive, 2 (last one on 0,1,2 chain), has this nasty whine when powered on. The other two drives work and sound fine. The faulty one's driver motor never stops when powered on whereas the other two do. The others must have the last one due to the terminator which functioned correctly in the chain. I have managed to pull the bad drive and managed to get the two working ones to work with terminator resister moved to drive 1. I put 2's (bad drive) large electronics board onto 1's drive mechanism and it works fine. That leaves 2's drive mechanism as being bad; either the small circuit board or the drive motor. Also, when 2 is selected the red LED does light up, but no diskette can be read. Something is forcing the drive motor to stay on or the drive motor itself is defective. Any suggestions? I plan to put 1's (good drive) small electronics board onto 2's drive mechanism to see if the drive motor control or the drive motor itself is bad. Left my soldering iron at work. :^(