Running under very hot water for about 30 seconds and very carefully moving the joints will loosen up the sticky/tight spots on the figures. I do it to just about every NECA figure that doesn't have clothe or electronics. NECA has a history of super sticky/locked joints because they paint over them.
Paint rubs off a lot too because of how and where they apply it. In my case, it's usually on the joints, mainly the elbows or back of the knees where my paint comes off.