Vindication, Book I, 1931, pp.338, 339 states:
There was a measure of disappointment on the part of Jehovah's faithful ones on earth concerning the years 1914, 1918 and 1925 [and 1975], which disappointment lasted for a time. Later the faithful learned that these dates were definitely fixed in the Scriptures; and they also learned to quit fixing dates for the future and predicting what would come to pass on a certain date, but to rely (and they do rely) upon the Word of God as to the events that must come to pass.
So, no more predicted dates. Just events.