Hi Tom,
It sometimes takes a lot of wiggling and fidgeting while turning the crown back and forth to work a movement out a case. They usually end up coming out. In most cases after a final sleeve adjustment is made by a previous watchmaker the movement will be removed so that he or she could grasp the square to fasten the crown down onto the stem and THEN the movement is re-installed. So if it went in it should come out right. Not always the case though. The watchmaker may have had enough room to tilt the movement out a bit and reach in with a stout pair of tweezers and grab the the stem and have enough of a grip to add some type of adhesive to the thread and snug the crown down a little. If no adhesive was used then you should be able to find that same amount of space to reach into and possibly break the crown loose. Break as in release I mean! 
Edit: I see that Chris was posting at the same time as I was…his suggestion about using a soft landing area is a GOOD one!
Bob