Abstract: A head positioning apparatus for a magnetic drive for positioning the head of the tape drive relative to the several tracks on the magnetic tape. The positioning apparatus includes a lead screw driven by a stepper motor, a half nut on a carriage carrying the head and threadably engaging the lead screw, and a spring clip secured at its opposite ends to the half nut and embracing the lead screw and acting to urge the lead screw laterally relative to the rotational axis of the lead screw into positive threaded cooperation with the threads of the half nut so as to preclude lost motion between the lead screw and the carriage during movement of the head between adjacent tracks and so as to preclude movement of the head following arrival of the head at a specific track unless and until the lead screw is again rotated by energization of the motor.