When you have a drive with a single bad head, do you image what you can from the drive before you do a head stack, or do you just dive right into the head stack?

Also, can you give me any pointers for testing the heads from the hermetic block? Do manufacturers provide pinouts or do I have to just compare to a working drive?

Hello,

Measuring the heads on case of unknown dead head is useless.
You can't be sure wich case do you have, like lifted/tilt/crashed head, or dead GMR.

The best thing is checking in cleanroom before trying to copy.
The most drives the internal strip size is very low.
So, the partially saved data is not too useful.

Regards,
Janos

If possible, yes. The connector leads to preamp not to the heads directly, but is useful too - it's better to test at pcb level anyway.