Not to be the bearer of bad news, but I'm 100% certain that your problem has nothing to do with the PCB. In the 200-300 or so of those drives that I've done recoveries on there hasn't been a single one that was a failed PCB. That model has extremely weak read/write heads and known firmware glitches that'll make it stop working. They actually had so many fail they are in a class action suit in the USA now:
https://www.extremetech.com/extreme/222 ... lure-ratesIf the drive is clicking and spinning down, you can bet it's failed read/write heads. If it sounds to be spinning normally, it's probably an issue with the media cache which will need to be disabled in the firmware code. In either event you'll need professional recovery. Since you are in the UK I'd recommend you go to
http://pcimage.co.uk