UV Texture problem

Does anyone know why the grey lines are showing up near the rear of the cockpit?

hard to say without seeing the unwrapped UVs. did you select those faces and check them in the UV editor to see that they are positioned correctly?

I found that the problem was a set of verticies around the cockpit, so that is now fixed.
A new problem has been found in the wings. Some areas will get painted, others will stay dark.