HSA Swap on Fujitsu MHW2120BH: disk spins up but never ID's

[mediaman]

Hi There,

One here to please ask for help. I received the disk with click of death. Head swap (perfect match donor, one month early fab) and the disk now spins up fine, no clicks, no spin down, but never ID's.

I took the HSA back off and replaced on the donor and donor 100% after media scan. I did this with two donors (both a few weeks earlier fab than patient) and same.

I am thinking maybe one or more of following:
1. there is some PCB damage and disk is initializing but sata bus not reading
2. Fujitsu disks are strange and spin up even with bad heads (spare data in ROM?)
3. some firmware corruption, maybe related to my HSA swaps?
4. I should try a HSA a little later fab. date than my previous two attempts (but I still don't understand why disk spins up and not ID, of HSA was not compatible, it should spin up, search, and spindown??)

Help much appreciated.

Thanks.

[mediaman]

there is one extra possibility here: anther local DR place checked the disk first.

Before I have know these guys to "tweak" disks to make sure only they can recover them after the quote stage. I am wondering of they swapped some parts or did some FW change?