Well, here's hoping mine doesn't develop such problems, but so far mine is great.
I've peeped down into the head of mine and I don't see any locktite/glue on the pill, but an initial attempt to unscrew it failed so not sure. I used the same tool I use to open up tails on Fenix and the NiteCore, but the tips are really too thick, I'll have to try something else sometime.
I've found that you have to unscrew the head about 1/8 or more in order to not flicker between high and user modes, but that's not a big deal, I'm used to that on my P2D. The distance between modes is actually less on the NiteCore, so less twisting, so that's good.
Only kind of annoying thing is I have to lock out the tailcap, but it's mainly because I have a GITD aftermarket tailcap and I think it's shorter than the NiteCore tailcap. I'm going to try to shave off more of the inside of the GITD tailcap, otherwise swap the NiteCore one back in.. I never noticed it 'flickering' in my pocket like I do now unless I LOTC, so this is not any fault of the light itself.
So far I'm very pleased with my light.