Mine has an aluminum piano hinge attached to the bottom of the door with 1/8" aluminum POP rivets. The other half of the hinge is attached to bottom of the frame with the same rivets, some are hiding under the weatherstrip. Is it the hinge that is broken or did the rivets pull out? You should be able to find the hinge, POP rivets and a rivet tool at Lowes, Home Depot, or similar place. If you need to replace the hinge, the replacement may be longer than needed and you will have to saw it to length. An 1/8" drill bit should take care of the old rivets. Start by attaching the hinge to the door and then attach to the frame. Trial fit everything before drilling new holes if needed. If you don't feel comfortable doing this, then the dealer or the neighborhood handyman might be an option.
Air Safe Hitch, Reese Dual Cam 800#, Centramatics