You may already know this, but the model 47 is just a deluxe version of the model 20, or 20a. With it's casehardened frame, and checkered buttstock, they were very good looking guns. parts for the model 20 variations will work fine, if you can find someone with these. I would guess offhand you might have a carrier problem, and that would be where I would start looking.
Curious how you came up with the 1930-31 time frame? These guns are tough to pin down, as there are no records, and nobody knows what serial number they started with. According to Brophy, the lowest number is 12xx, but without knowing where they started, or how many were made, a date is pretty hard to pin down.