The eye cup is composed of an inner collar and an outer collar. Best I can tell from the photo, it looks like the outer collar has separated from the inner collar.
Zeiss USA will send you new eye cups for free if you call them. I believe service is now in NY so they should be able to get them to you soon.
It looks like the inner collar is still screwed onto the eye piece housing so it would have to first be unscrewed before screwing in a new replacement eye cup.
Here is a thread with some photos of the eye cup that may help and it also goes over the best way to screw in the new eye cup.
http://www.birdforum.net/showthread.php?t=336799
It looks like you have the gray body SF. Zeiss did an update to the eye cup last year when they replaced the gray body models with the black body models. The only difference in the eyecup is the new design has two intermediate positions rather than one intermediate position. You should request two of the new design.
