I am trying to model a helmet. I have created boundary surfaces for the upper and lower part of the helmet. I then mirrored those surfaces and created a boundary surface to seal the bottom. I knitted all of the surfaces together and created a solid. The resulting surface has split lines along the 4 quadrants of the helmet. I need to get rid of them. They are creating all sorts of disjointed lines when I project curves to try to add more features. Any ideas?