You must get the book 'Captives of Concept' by Don Cameron (hope that is spelled correctly)
You can go to Lulu.com and download it right now for five bucks, then refer to it on your computer.
"Captives" says in chapter 3 that the Proclaimers book has all the explanation you need about the
printed truth of the matter. As far as talks or otherwise, if it isn't verified in print, then it isn't necessarily
so.
Proclaimers, p. 46-47 says that "Nelson Barbour succeeded in convincing Charles Taze Russell that
Christ's invisible presence had begun in 1874.
Proclaimers, p. 133 mentions this again along with a footnote explaining that "a clearer understanding
of Biblical chronology" was published in 1943 in The Truth Shall Make You Free then refined the next
year in The Kingdom Is at Hand.
The Proclaimers book, p. 133-134 even admits this: "Attention was later drawn to this [belief that Christ's
invisible presence had begun in 1874] by the subtitle "Herald of Christ's Presence," which appeared on the
corner of Zion's Watch Tower.
The WTS figured if they printed all their own mistakes honestly, but spread them all around the huge
Proclaimers book, opponents could not say they were dishonest.