That one as well as the screws on the engines are a bastard to get out on Ramjet. I had to take a small slot head screw driver, press down hard on it while turning it with a pair of plyers. as for the "smudge" its just my cheapo camera doing something weird.
Yes, I noticed that too. I didn't take that part apart, but I will try your method. Obviously, they over-tightened the screws a little. You painted all these little parts individually?