I've had the opportunity to work with a number of different Floyd licenced trems. Usually the arm can be adjusted to swing or not swing by adjusting some bolt or nut on the back side of the guitar. Often I've had to search for a "hex" wrench or a small open-end wrench that will fit thru the back of the guitar. One model had a nylon washer that would break frequently but the washer was needed to prevent the swinging of the arm.