Hi,
It seems you don´t have a clue about it´s function nor where it comes from...
The circuit probaly is more than 30 years old.
Why are you so interested in it´s function? There most probably now a remore modern solutions for the same.
You post three photos, all show the same view.
We can´t see the wiring nor the marking of all parts.
But even if we do .. it still wil be hard to find out it´s function ...
and if we do .. it will be hard to find a circuit to use it in future.
My personal opinion:
Isn´t it a waste of time to look for a problem that you didn´t have before?
Klaus