kokomodo

I have a 2008 xD. The middle rear seat belt is supposed to clip into an anchor on the ceiling when the rear seat is folded down. The first time I clipped the seat belt into the anchor, it would not come back out. I read the manual, fiddled with it, but it did not seem to behave as expected. Is there supposed to be a spring inside that plastic housing that releases the clip when you push the belt end into the housing (like a ball point pen)? Does anyone know what that part is called? I've had trouble locating anything like it on the web, and have not seen any reference to others having trouble with that part.

-Kokomodo