With mine one arm had the forearm armor stuck midway, so it was still possible to put everything together under the wing but the gun was just a little lower, definitely not as flush as the other side. Eventually I was able to get that armor moving and helped to have it right under the wing.
It is not the only issue, if you push the arm full into the wing tabs, guns will point down, but if you dont, the panels wont make one flat surface.