Personally I believe all left the factory with the plain crown without AP letters. This is merely based on discussions with AP personnel, and all those which I have seen myself. I could be wrong of course!
I dealt with precisely the same situation 2 years ago with mine, with them. They simply will not give you the old crown back, and will not perform the service without replacing it. Personally I feel that the AP logo crown does not reduce the value and on the contrary, that knowing that the movement