When this drive failed, it wouldn't even spin up after restarting the machine.
However, when fitted with the new pcb it does spin up, but it still fails to initialize, and no movement of the drive heads is evident.
I am beginning to think that both the drive mechanism and electronics may be damaged, so I'm reluctant to try the new drive mechanism fitted with the original pcb in case it too should suffer damage.
If it makes any difference, I did notice that the original drive and new drives have different firmware versions (the original has version 3.03 firmware and the new one version 3.32), otherwise they appear to be practically identical.
I bought another of these drives from eBay last night after I had discovered how easily they can be disassembled, and it was dispatched this morning, so I will soon have another pcb to try with it.
If the content of the original drive is lost, then I will recreate it as far as possible on one of the new drives and mirror that with the other drive to prevent this happening again. After all, these drives now cost an order of magnitude less than the original drive did ten years ago when it was new.
Whatever the outcome, I will still upload some pictures if anyone is interested.
Edit: If the original drive mechanism is damaged, it hasn't had a detrimrental effect on the new pcb, because the new drive still works fine when fitted with it.
(I have been taking anti-static precautions throughout.
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