Check cheaper cramps before use. The pin that secures the moving head to the screw is often in the wrong place. Drive it out with a pin punch and check that it sits in the groove in the screw, when under pressure. If not put washer(s) under the head to shim it into place. Ignore this and after a few uses the screw will part company with the moving head. Applies to Dakota "records", Ax, and Silverline expert types.