1975 -What the Watchtower doesn't want you to know, page-6

The 1975 saga that you refer was by no means the only example of Watchtower having to retreat with it's tail between it's legs.
I have posted a more recent example: Here it is again : “Tell Us, When Will These Things Be?”
THE WATCHTOWER (STUDY EDITION) JULY 2013

Extract:

WHEN DOES THE GREAT TRIBULATION BEGIN?
3. In the past, what was our understanding of the timing of the great tribulation?
³ For a number of years, we thought that the great tribulation began in 1914 with World War I and that “those days were cut short” by Jehovah in 1918 when the war ended so that the remnant would have the opportunity to preach the good news to all nations. (Matt. 24:21, 22) After the completion of that preaching work, Satan’s empire would be destroyed. Thus, the great tribulation was thought to have three phases: There would be a beginning (1914-1918), the tribulation would be interrupted (from 1918 onward), and it would conclude at Armageddon.
4. What insight led to a clearer understanding of Jesus’ prophecy about the last days?
⁴ Upon further examination of Jesus’ prophecy, however, we perceived that a part of Jesus’ prophecy about the last days has two fulfillments. (Matt. 24:4-22) There was an initial fulfillment in Judea in the first century C.E., and there would be a worldwide fulfillment in our day. That insight led to several clarifications. *

Another disappointment for the faithful followers. Indeed further examination. Why? Because they got it all wrong. Not a good record for an organisation that claims to be God's representatives on earth.

But does the fact that stumbling blocks have occurred . automatically disqualify an organization from being God's people?

Watchtower has been preaching their failed doomsday theology without their flagship prophecy coming true for well over 100 years with a constant stream of revisions. This alone should be a red flag about the authenticity of the organisation not the mention their exclusive rather than inclusive policies.

There was an initial fulfillment in Judea in the first century C.E., and there would be a worldwide fulfillment in our day. That insight led to several clarifications.

And so it goes. "Our day" never comes and people cling to hope even though the hope provided always turns out to be hopelessness. Oh, well the organisation has grown very wealthy from selling what has turned out to be no more than a cruel pipe dream for some.