The guys at WTOR something do not fully adjust the box right, they depend on your finishing it up on the truck. Is there a bit of the screw sticking out of the lock or jam nut? If so, then you still have some adjustment left. If the screw is flush or lower than the jam nut then you do not have any adjustment left.
Look at that first and id you do not know how to adjust, come by or hit some one up in the club that does.