Well to my knowledge, western digital does not replace that type of parts. you might need to contact a data recovery service to see if they know were you can get that.
I don’t understand what you mean when you say that you plugged your MyPassport into a “faulty hard disk”.
That said, a straight PCB swap will not work. Most modern HDDs store unique, drive specific “adaptive” information in a serial EEPROM chip. This chip, or its contents, needs to be transferred from patient to donor. In WD drives, this chip is usually located at U12. If you upload a photo of your PCB, I should be able to help you identify the EEPROM.
The following PCB suppliers offer a firmware transfer service, either for free, or for US$10:
I would advise that you avoid those suppliers who don’t tell you that a board won’t work without modification. Often they will attempt to obscure the requirement for a firmware transfer by deceptively describing their products as being “for data recovery only”.
Alternatively, if you are not adept at soldering, your local TV/AV repair shop should be able to transfer the chip for you.
Some PCBs do not have a discrete serial flash memory chip. Instead they store the adaptive data inside the Marvell MCU (the largest chip). In this case you will need a “PCB adaptation” service.