I lied. Opened up the drive again because it once more stopped working.
Removed the stepper motor and *oops* the top two bolts were held in using washers and bolts INSIDE THE DRIVE! Eek. So I had to remove the cover and fish them out, then put them back in place.
The inner bearing of the stepper motor received a couple of drops of oil and it finally got rid of the crunchiness you could feel when turning by hand. Since I had the drive open, I put the smallest amount of oil on the shaft.
It's all back together now and passes the self test 100% of the time. Won't boot - but whatever, that's nothing new! Still gives me a happy mac.