Don't know if you have a backup of this volume's data or not. Using that to a new HDD is the #1 best choice.
If you know for sure the problem is with the PCB, you can replace the PCB with an exact Model # & Rev # of a Conner HDD. It is finicky but can be done. The firmware on the PCB has bee low level formatted and timed by the manufacturer for the HDD, so if it's not exactly a replacement, it won't work.
You never want to open the HDD's cavity in that any microscopic dust will ruin it's function.