first off,
push the site (wobbley thing) downward and tward the rear stock it should pop off of the gun.
then ull see theres a ( shaped spring under the site. and it go's under a lip on the rear of the site housing on the gun, what you want to do is tap the lip that holds the ( shaped peice of metal in there, downward because it is bending upward from the stress of someone pulling the rear site in an awkward direction.. lol
ull see what im talking about when you get the site off of the gun. just take the site apart and inspect the part the site pops into, i cant explane it for crap. its only 2 peices should be pretty easy.
then reasemble it, ull notice it will be alot harder to pop the site back in there, when you get it poped in it will be tight again.