You unscrew it.then take out the spring and clean it.
Next you tale out the (RB) button,clean that piece.
Then you put the spring in first...then put the (RB)button not top of the spring(be sure it shows/pokes out so you can see it.finnaly, screw the pieces back together
How the controller made into 2 pieces,that's why there are screws to hold it in place
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For people w/a wired controller try to screw on the screws on tighter
Or unscrew it and fix that thing that gets on the top of the controller