that sounds like there is something dislocated
[http://www.vidoemo.com/yvideo.php?i=YTl1SVVscWuRpRjh0Z1E&how-to-open-and-close-an-xbox-360-wireless-controller-easy-mod-service-now-in-business|here]is a video where you can see how to disassemble and reassemble the controller
and maybe you want to mod your controller a little [http://forums.xbox-scene.com/index.php?showtopic=581887|bit] - if it's still open....