Is there any way you can take the metal clasps OFF the wooden frame (ie, are they attached with small nails or something)? I've never seen a pocket no 3, so I don't know. If you can, you can heat them up using a torch and cool them off so they won't be work hard and brittle. They'll bend much more easily and won't snap.
Just be careful. Are these cameras expensive? Maybe you could find another one just to experiment with....but with metal this old, I'd imagine annealing would be the only option to be sure they won't snap.