In the second pic it should be locked into place. If it is still moving then the set screws on the back need adjusted. I think you screw then in to tighten it up. I have the same fence I can take some pics of mine if it would help you. Mine may have a pad on the face of the metal flap piece. The set screws also need adjusted to square the fence to miter slots which should square it to the blade also since the blade should be squared off the slots also.