Hi Realist,
For me the turn around came from my own observations and not from direct external information which, as others have stated, would have been automatically discounted. I began to notice that though the Elders preached that we should not get married, have children, buy houses, or get caught up in making a living because the End was so near and the preaching work should be our top priority that they themselves were doing exactly what they were warning the rank and file against. This was especially true following the 1975 "disappointment" and I also noticed that the Society was always bragging on all the new building projects with many years til future completion and equipment they were investing in as well, hardly the acts of people who know for a God revealed fact that the big "A" was about to start any day. In short, I began to wonder just how seriously the Watch Tower Big Wigs took the whole Armegeddon thing right on down to the Elders. It seemed that the fear of the big "A" was just for us lowly publishers as the higher ups went about their business as if this old wicked World was going to be around for another 100 years.
I also saw the bizarre lack of concern that the Watch Tower Society had for eating blood in unkoshered meat when we were all expected to die rather than take a blood transfusion based on exactly the same scriptures which were clearly talking about improperly slaughtered meat. This made no sense to me at all and I never got a straight answer. Counting service time also seemed unbiblical to me as I couldn't imagine the Apostles turning in their hours to be counted.These and an ever growing list of other slowly expanding logical condradictions caused me to question the truthfulness of the Society in general and that is when the external information began to click into place and made perfect sense.