Hi Molly -- Welcome to the Forums!
Too bad about your hinge. You'll probably need to troll around Airstream groups a while before you find the right item. I would suggest posting a digital photo in a wanted ad because some parts were used during several years' production and on more than one size Airstream. There are free classifieds here and at the
Vintage Airstream Club. Perhaps the classifieds at Airstream.com? Cast your net as wide as you can. You could also try contacting
Colaws RV Salvage in Carthage, MO. Good luck in your search!