I love lockets! They always sell fast whenever I've listed them!
Typically, I've found hallmarks on lockets on the inside centers, like in your smaller locket, and also around the inside frame and edges. I wouldn't be surprised a hallmark could be under that photo, too.
Here's the maker for the smaller locket.
Glad I could help out! 
In my opinion, I wouldn't clean them. Unless you really know how to do it, I would leave it up to someone with more experience or a professional jeweler. It's also a huge debate with collectors whether to clean vintage and antique jewelry. Once the patina and the verdigris is removed, it can never be replaced except for the same amount of years it originally took to develop. Especially with having the original photo in that one locket, it all has a lot of unique charm and character as it is.
