There are a few things you can do , On the side the pad not moving you can screw that screw in more to make the arm ?pad move away from the rim , or you can loosen the screw other side so it will move inward . What you want is the arms/pads to move the same distant at the same time . The other thing you can do is unhook the spring arm if there is one behind the arm and bend it outward or downward a little ,then reconnect it back onto the arm and that in itself should move the pad away from the rim .