Ok the same thing happened to me.I opened it up and found that my line was snapped where it connects to the air tank.Nothing a little super glue can't do.
Ok the only reason that i had to do this mod is because 1.i couldnt find the right stefens of nerf bullets anywhere.2.I really needed a loser weapon and it is a great one with its dead aim am speed. I placed a crayola on top of it to 1.Store a bullet,Or 2.use it as a scope.