Ive been thinking. The gas Tube on my AK is a pain to It falls right in but you have to pry it to get it started out. Could trunnion tilt be the reason? How hard would it be to fix if that were the case?
Probably just a tight fit. I leave the gas tube lengths a little long (or place the gas block a little close to the receiver) when I'm assembling them, so they are always tight on my AKs. It could be that and/or "carbon fusing" of you gas tube and rear sight block. I never remove my gas tubes...except for this one time...when I fired a few hundred corrosive rounds through one and accidently left it outside for a week of rain...bad combo. Lots of work on that AK afterwards...