Yes, I would not trust myself to fix that particular problem either.
I think the AA diopter is a functional but cheaply made piece of kit, like the old Milbro job. I have a Williams peep-sight on my HW30S and with the square blade it can shoot into a 20mm circle at 30 yards. The Williams (Beeman) sight has a much bigger aperture than the more 'target' orientated sights, which may lose a little accuracy but means you can shoot in a variety of light intensities. I tried one off an old Walther 55 target gun and it was just too small to let much light in, they are made for brightly lit indoor ranges. Or people with younger eyes....