This type of corrosion could be caused by a previous owner being of the type that produces noxiously acidic sweat... There are a few on here who know what I'm talking about and some stories I've read where they can only use a set of strings once! One guy got his guitar back from a loaner to a friend and it was ruined in such a way that they had to guess it was the guys sweat that did it! I would think just a Gibson replacement would suffice since the source of the sweat has been removed... Unless..... it's YOU!!