I feel that my question is probably too wide, I'm willing to focus my question more if needed and possible. Please comment.
I have a hard-drive (2.5" Toshiba) which was installed in a notebook. The notebook fell from a table (on the side) while running. Since then the disk makes the click-of-death-sound and is no longer recognized either by the system or when attached to a SATA-USB-adapter on another PC.
In the past, for another hard-disk with the same symptoms, I did/tried a transfer of the hard-drive-heads from a working disk to the non-working one. I was unable to make the broken disk work again - the click-of-death remained. The data was lost.
At that time I only transplanted the hard-drive heads. I was as careful as possible. I saw that the heads of the broken drive were visibly damaged. The donor-drive was the same model, but not the same creation date.
When done, I let the disk run while being semi-open. I saw what created the click-of-death: it's the heads running over the whole disk and then returning abruptly onto their parking position - this is when it is clicking. The controller instructed the drive to do it again and again. It was surely looking for some "known-data".
Now, for my current broken disk, I have a working model of the same revision and date ready to be a donor. But I'm unsure - this time I really would love to get back the data.
What causes the controller to scan the disks again and again? What is it looking for?
Why does replacing a physically damaged head not help?
Is there some kind of calibration stored on the PCB which is adapted for the heads?
Transferring the heads was relatively easy. Was it too easy? Did I probably break something, even though I was really careful?