I guess I got lucky

I bough a bundle of three PB170s off the 'bay for a few bucks, they were "parts only" for sure as they literally came in several pieces each. Fortunately there wasn't a lot of damage where it matters (i.e. internals looked OK & clean, displays unscratched, etc), and the first screen I put into my own PB170 seems to work great! Ran it for several hours and no signs of any black creep.

Just out of curiosity, is the problem bound to come back eventually? I.e. are all PB170 screens "broken"? Or only some of them?