I have a marlin original golden 39M that was made back in 1977. i need some parts for it to get it functioning properly again. the parts i need are the complete cartridge cutoff assembly (cutoff, cutoff spring, and cutoff screw). i can only find parts for a 39A. i was wondering if anyone can tell me if the parts are interchangeable between both models or if i need to find parts for the 39m. any info you can give me would be a great help. thanks