I am speaking from personal experience, having been a member of that congregation during those years. As one of the ministerial servants there, I, too, had a full beard.
The crackdown started in 1981, when - for the coming District Convention - brothers volunteering to be attendants were informed "no beards allowed." After that, much must have been said in private to the various Bodies of Eelders by the Circuit Overseers. Certainly, immediately following each CO's visit, the elders seemed to have a lot to say about "when those articles came out about conscience" - and how "publishers thought that they could do what they liked".
This seemed to co-incide with when the WTS started making abig thing about "The Organisation."