The driver's door on my 1957 Eldorado Brougham will not latch closed. There's a rotary latch mechanism, bottom of the door's latch assembly, that spins freely with no resistance. It should be held in place ready to hit the striker. A broken spring was suggested and seems likely enough. I'll be with the car late next week to remove the door panel and look more closely, but just checking here first for some information that may help. Is this latch, or the spring, specific to the Brougham? I wonder if the spring replacement would be easily sourced, or is it something more complex, special? I'd appreciate any experience, information, advice, or help toward parts needed.
Not sure why the picture didn't attach, trying again
Unfortunately for you, the door lock is specific for the Brougham. However, it may have internal elements common to other models.
If you have a borescope, you can send it into the door with the window down to check things out without pulling the panels and you can compare to the other side. Most likely whatever broke on your latch is still laying on the bottom of the door.