In order to fix the paint rub issue you'd have to sand down the inner disc of the elbow joint. Using thinner,high quality paint in multiple very thin layers helps too.
it isn't just the inner disk, but the entire arm that rubs the elbow joint thanks to the bicep swivel. It is very hard to sand such a tiny space but I'll give it a shot next time.
Oh okay, I see what you're saying. In that case, if you boil and pop out the lower arm, you can sand down the area that touches on the upper part of the lower arm and then the lower part of the upper arm. That should help a bit.