Thanks for the reply.
So the PCB rev. ... is that a sticker on the PCB, or stamped on it?
If the PCB matches exactly, does that mean I can just "plug and play" the donor PCB in the original drive, or is there further configuration?
Is it possible to do the switch if the PCB numbers don't match exactly, perhaps with third party software?
What could cause it not to be discovered by the BIOS? Would a simple hardware problem do it, or a static discharge? Does the fact that it is not discovered by the BIOS mean that the problem is in the PCB?