Oops! this describes the sight on my BPS, not sure if A5 used the same sight.
On mine, which is fairly early, one uses two screws on the top of the sight to change elevation - tighten one and loosen the other and the "ramp" part pivots up and down on a pin. For windage, there are two screws, one at each end of the cylindrical part with the sighting notch. Loosen one and tighten the other.
There are no clicks or thread adjustments; you have to move both "by guess"
but when set properly they hold position and have given me no grief for 25 years.
Cheers,
Bob