What I found when working on my 47, the inner handle locks the door like it should, but the key lock from the outside does not have the leverage to work the same mechanism that the inside door handle does. The key lock does lock the outside handle not allowing it to turn so, in effect it locks the door by stopping the outside handle from turning, effectively locking the door. What I found while looking at the door latch mechanism before I reinstalled it. The key only turns a small plate to block the outside handle, not the same as the inside handle that block the latching mechanism.
