Listening to my MX980's right now and love them!
The only problem I have is that you know the rubber bits right on the end/outside of the buds, one of them keeps coming off, i'm lucky that i've always found it and now everytime I use them or take them out I have to check to see if the rubber bit is still on it. Is there any way I can get a replacement? They aren't as comfy without the rubber ring. Its just a shame for the price that they are and it started happening only a few months after use. I do take care with them as well like all my things.
I've had mine for over a year and I sometimes remove the rubber to clean it with baby wipes, but it's never detached by itself. Maybe you are not using the ear pads? Or maybe you have put them incorrectly.