Please forgive the attempt for pics first time around.
Diana built a great, beautiful gun accurate rifle and the worst engineered front sight ever to come down the pike.
The main trouble with that oddity is that there is little room to manuver there is very little purchase for the front screws
to hold onto,once you take it apart for a tune the steel screws eat away at less than3/32 of the plastic threads, then yer up the creek and you either buy a new sight or try to improve on
the present design.
I purchased an aluminum threaded insert 8-32x1"x1/4 OD as well as two screws could not find any thing metric in town,I cut the 1" threaded insert the width of the sight body, radiused the belly for the cocking lever that leaves about 3/32 metal threads for the screw to grab a hold of about 4 threads drilled the original hole to 1/4" used some super glue to hold the insert in place, it was a bit high wrapped some emery paper around a dowel and cut the radius flush with bottom of sight
reassembled the rifle.
The schnable screws have something to hold on to now.
Next time I'll use a steel insertwhen I find one.