I wouldn't open it up, especially if it's a Raven, you could risk catching some of the wires on something when you open it and tear a wire off and cause damage or something like that (it's a bit of a spider's nest in there if you don't know what to watchout for when you open up the controller), if you can pay to mail it in we can open it up and take a look - if just the plastic thumbstick 'top' needs replaced we wouldn't charge anything, if the actual 'post' on the thumbstick mechanism got snapped off that can take some work to repair, that's pretty hefty duty, so if that post got snapped you'd know how/why it did (dropkicked controller or using it to beat up on your friend lol)