The same thing happened to my set of Ne-7M's, but to the left one when removing its foam tip. I have them since august 2009. They still work and I can push it back in its housing, but it won't stick properly to it anymore, maybe a very small amount of glue could work?
Edit: Well, tried a very small amount of some super glue that we had laying around and it looks like its fixed so far.
Edited by t1n5l3y - 7/16/10 at 12:40pm