Hello Harley Kathy:
There are several places to look for the "hard to find" items for vintage Airstreams. An internet search should display many of them. I'm including a link that might get you started. It's their "on sale" items. They have many other items that are not listed because they aren't on sale. They do mail order and are here on the West coast.
Inland RV Center Inc.
Their list displays photos of window cranks & gears on sale. I have purchased a couple and they worked in my '67 Safari.
Good luck with your searching!