Further to Rogers note. The anti rotation screw is simple to replace if it's been unscrewed out, but a bit of a sod if it's been cut-off square. That's because you cannot get a drill onto the old cut-off screw past the erector cell collar and ocular housing. I have an 8" long drill that goes down a curved steel tube that..... anyway, it's a bit of a sod!
As for those that won't send innocent/lawful parts abroad, then I say just find someone that WILL and get the parts sent there, innocently re-packed and on their way. That's what I did with some AN-PVS2 parts. And we're talking just the rubber protective eye and OG end caps here!