I expect this will be an easy one for Peter et al - I was shooting my No4 Mk 1(T) with iron sights on Sunday, for the first time. I found the adjusting screw which elevates the slide has a "rotational floppiness" about it and not a definite click as it goes round.
What do I need to replace, in what sequence do I take it apart, and what goes wrong when doing it the 1st time?
I attach a diagram of the parts to help the explanation make sense to me...