It's important to know when a PCB is bad and when swapping it with a donor PCB could work. A thorough diagnosis is required. Embedded in a Firmware on the PCB is "adaptive data" that is unique to the hard drive it's attached to. This "adaptive data" includes information about the hard drive's heads, its firmware version, any bad sectors in the drive's service area, and more. It's possible, if the "bad" hard drive is completely dead, that swapping the PCB may get the hard drive spinning again. However, it will likely start clicking, or at least not provide any access to the user data area of the hard drive. In this case, the way to successfully perform a PCB swap is to move that unique firmware data from the original "bad" hard drive's PCB to the donor PCB. This is accomplished using spe.
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