look for a bolt that is just slightly bigger and screw it in a little ( say 1 turn) then undo and the screw in again a bit further and then leave for a min and then undo again. keep repeating until in all the way. Had to do this on mine as it had crossed threaded abit. just take you time working it in and out and spray with wd40, it should recut the thread. If not confident do not try this.