Here is the board from the 9122D cleaned up and tested. Next step is to coat the tracks using the new solder mask. Yes, I also know that cleanening isn't a word but I thought it was still appropriate...
Thanks - Sorry about the delay but this comment just appeared in the RU-vid Studio - Wasn't there a couple of days ago and you clearly posted some time ago so I can only blame the Studio Beta :)
I got a spray can of PCB sealing lacquer from the electronic shop to totally seal my PCB from every angle. I would have a crack at resoldering the traces to see if it gets rid of those dark spots.
Looks like it cleanened up pretty well! Wonder if that drive unit was connected to a piece of HP laboratory/medical equipment at some point in its career and was exposed to chemical/reagent fumes?
