I just bought a running 47 this summer. I have 3 others, but could not get any to run. If the rotary valve is worn, they won't run very good if at all, won't hold crancase pressure. This one sounds really nice, 4 cycles easily under no load, and evens out while cutting. It sounds a lot like the 2- man McC's. It's a fun antique saw, but would be chalange to repair. This latest one came with an operators hand book, which really helps a lot. I also found a parts book for it. Can't imagine trying to do anything to this saw without these. Maybe thats why I couldn't get my first ones to run.
Scott