There's plenty of ones where they blatantly say that 1914/1925/1975 will be the prophesied time and then later on say "Some Christians thought..." As you show with the lecithin example, they do this an awful lot. Shift the blame onto the R&F when it came out of their own mouths.
This isn't so much to do with WTBTS publications as to do with JW's themselves, but I've figured a way you can expose their double standards with just a few questions.
You: Do you believe that the GB is God's "faithful and discreet slave" who carry out HIS commands directly from HIM?
JW: Yes.
You: So how can you explain failed predictions/changes in doctrine? (eg blood fractions, disfellowshipping)
JW: The GB are imperfect men.
You: But you say that the GB carry out direct commands from God as they are his chosen "faithful and discreet slave". How can any of these commands be wrong or be changed? They are from a perfect God! This therefore means that either God is deliberately getting things wrong or changing things OR his "faithful and discreet slave" are getting the messages from God wrong and therefore their commands cannot be trusted as commands of God!
At this point cognitive dissonance kicks in and any reasonable or rational conversation ends. But it's good if you want to plant a seed of doubt in the mind of a JW that will hopefully grow and make them realise TTATT one day.