In article KnANm.23$C3.9@llnews,
John T wrote:

My partner and I are having a discussion about how the original pilot's
shoulder belt tensioner is supposed to work in our 1978 Arrow III.
Currently, it always applies tension, which bothers him a bit during
long flights. He thinks it should latch or ratchet so that once it
finds a position, it should stay put without the tension tugging on him.

To the best of my knowledge he is correct.
fwiw - the tensioner latches on my 1974 Cherokee 140.