Ok I dont think its a 42 ,early 42s were zinc then steel..
If it has a flat spring ,not a coil spring under the cam (the tab that flips up and down when open/closing lid) It is after 38
So if it has a flat spring , it would be between a 1938 and 1946 because of 14 hole chimney.
If it is made out of nickle silver, not zinc or steel (42- 45) or chromed brass all other years, it is 1946.
I have not found anything on the case markings yet But it would prob be easier if we knew what they were JNS, J S with a mark between them ? I dont know.