This paper reports on the design, construction and testing of the manipulator arm that is to be fitted to UCTs Urban Search and Rescue Robot (USRR), named the Ratel. Of particular interest is the utilization of adjustable backlash dual lead (duplex) worm gears in the manipulator arms joints. These gears were incorporated into the arms three most significant joints, i.e. the turntable, shoulder and first elbow. They are implemented to increase positional accuracy of the end effector and to reduce shake in the video feeds by removing free-play in the joints. Custom gearbox housings allowing for adjustment of these gears, as well as other requirements such as permitting continuous rotation and internal wiring, were developed and are discussed in detail in this report. Conclusions are presented based on the authors findings.