When did Waltham start to produce their own stem wind Model 1857 movement. I just got this one, #597037, pinned dial, key set in a Fahy's nickel case today. I am in the process of stripping it down to clean it. It had a broken mainspring of which I had one left. It is over sprung with 15 jewels probably making it a fairly high grade for its day. It is kind of strange that it is still key set.