We've bought a 1950's home and started doing minor reno's to the place. My partner loves the old door handle & locks so I'm trying to get them all in working order. One of the latches on the lock doesn't go in or out so we can never shut the door fully. When I took it off the door a toothpick sized metal rod fell to the floor (I've placed it on the lock in the photo). I presume this is the problem, but can't figure out where it would reattach. Any help would be great :)
I don't know much about locks but my first guess is that it was a spring and hooked up something like this:
the 3 notches would allow adjusting tension. Should be easy enough for you to verify by pulling the remaining part to see if it helps the lock work better.
There is probably more to it though. It's not clear in your picture if the right plate/lever might be interacting with it. There's a bright spot at its end, is it curved up such that it might get in the way of the wire?
I also suspect the slightly curved end had a purpose, such as changing tension when the deadbolt moved (assuming that's what the top right brass colored piece is). I have no idea why that would be useful but it makes no sense to attach it that far out otherwise.
If you have another of the same model which is working fine, open it carefully and look at how all the parts move.