Most JWs won't even look at old literature in the original publications obtained at Kingdom Hall libraries or on WT CDs. In those situations, it's not belief that "apostates" have doctored the literature so much as it is fear that the actual literature is as bad as "apostates" say it is.
I think most JWs are actually afraid of what they might find. If they do any thinking (at all) on their own, then they have already encountered issues that were inexplicable to them. Their cognitive dissonance kicks in, they set it aside "on the back burner" and they ignore it until they face another issue. Rinse. Repeat. Thus, they make great efforts to avoid stumbling across another issue they can't explain. It's an uncomfortable feeling. So many (most) JWs have gambled "the farm" on the JW doctrines and they can't/won't face the possibility that they have lost it all. Even if THE END (TM) never comes, they can still always claim it is CLOSE! One day closer than yesterday!
The fact is, they can't handle The Truth About The Truth!