I don't see how parts to a camera which is as much as 75 years old could have any patent protection. In fact, I don't see how you couldn't make a part-for-part clone of the camera, except the branding. But I'm not a lawyer.
I've contemplated getting a lathe and learning how to use it just so that I could turn out steel copies of brass gears. I'm sure I must be underestimating the difficulty and overestimating the demand for specialised camera replacement parts.
It's probably as cheap to make 50 as it is to make 1 part, so why not? Find a price point that pays you back and advertise on eBay or wherever. If eventually it catches on and the price falls to the bottom, maybe we'll all be winners. I would pay $2 and wait a month for shipping to repair a $25 camera. I'd also pay $10 to buy one made in the USA and shipped within three days. I won't pay $50, ever.
I am skeptical there is much of a market for these parts, or much money to be made. I'm not a camera technician, so I'd probably have to hire someone to do any major work. I'm fairly certain I could buy several cameras hoping for a working one for the same price as the labor to fix one.