Hi all, I am a gunsmith at a local gun store and am working on a customer's S&W 64-7. It came to me missing the extractor, so I ordered one and tried to install it. It fit the cylinder just fine, but when fully assembled with the cylinder closed, the hammer cannot be cocked and pulling the trigger will advance the cylinder but not fire. I've attached a couple of photos showing the new extractor installed in the revolver, along with a second cylinder from another 64-7 laid on top that works fine when installed. Perhaps there is some fitting that needs to be done? Any help or clues would be greatly appreciated. Thanks!