What are your other procedures for a probelm like this?
It's pretty low-tech, to be honest. Your issue sounds very much like the problem we had with the 4X optical drive in a PowerMac 6200/75. It made all the right noises but nothing would mount. I had an Apple external CD-ROM so used it until we retired the 6200. Shortly before parting out the 6200, I decided that looking inside the deceased drive would be educational and, as the drive was not working and out of warrantly, would be a free lesson.
I removed the drive and took off its top cover to expose the mechanism. I could see no obvious damage or parted wires. The read head was mounted on a rail of plated steel rod. I nudged the "head sled" assembly where it attached to the rod and it was apparently stuck. A slightly harder nudge freed it and I moved it to the limits of its motion several times before returning the head to its "parked" position.
I reassembled the drive and put it back in the computer. I had one more test for something else to run and, in the process, thought to try a CD. The darned thing worked perfectly!
After parting out the 6200, I installed this same resurrected drive in an 8100/80 that had a slow 2X drive. That was probably 6-7 years ago and the drive still works perfectly to his day.
The bottom line is that it seems some head sleds can get stuck on their mounting rail from lack of use. There is little to lose by opening the drive and seeing it you can manually free it.
