In the old drives of 5" HDDs the head stepper motor shaft was external, and if a drive got stuck a slight twist of the stepper shaft would unstick the heads after which the drive would spin up (well, as long as it didn't rip heads off the HDA so it was always a calculated risk).
Happened to me when I got a call out to a large UK outfit who'd have an extended power cut and knew recovery was going to be fun. First stop was a particularly critical PC which had exactly this problem, so open the case, touch the HDD just right and off it went - happy with that, and to the next item.
Anyway, the recovery operation went well, and this particular incident came floating back by way of a hushed comment from a manager a few years later about this tech who'd come in to help with the recovery, and who'd "...laid his hands on the PC, and it came back to life!" :)
Happened to me when I got a call out to a large UK outfit who'd have an extended power cut and knew recovery was going to be fun. First stop was a particularly critical PC which had exactly this problem, so open the case, touch the HDD just right and off it went - happy with that, and to the next item.
Anyway, the recovery operation went well, and this particular incident came floating back by way of a hushed comment from a manager a few years later about this tech who'd come in to help with the recovery, and who'd "...laid his hands on the PC, and it came back to life!" :)