This is from the repair CD:
Automatic Electric Antenna
Removal
1. Using an appropriate tool, unsnap the cap from the antenna base and remove the radio antenna base cap (18A927).
2. Remove radio antenna nut (18865).
3. Turn the ignition switch (11572) to the ACC position and turn the radio chassis (18806) on to extend the electric antenna.
4. Firmly pull the electric antenna out of the electric antenna motor.
Installation
1. Check the plastic cable end for a slight taper. If the cable appears to be broken, a section of the plastic cable could be inside the electric antenna motor. To remove the cable, proceed to Removal and Installation, Antenna Motor, Electric. If the cable is not broken, continue with Step 2.
2. Obtain a new electric antenna. Position the plastic cable so the teeth are facing the front of the vehicle.
3. Manually extend the electric antenna, then insert the cable into the electric antenna motor until resistance is felt. Turn the cable slightly left and right to fully engage the cable into the motor gear.
4. Have an assistant turn the ignition switch to the ON position, then turn the radio chassis ON and OFF. Apply light downward pressure to the electric antenna as the electric antenna motor starts retracting. The electric antenna motor will wind the cable into the electric antenna motor drive unit and retract the electric antenna sections.
5. Install radio antenna nut. Tighten to 9.5-10.5 N-m (84-93 lb-in).
6. Install the radio antenna base cap.
7. Cycle the electric antenna motor several times to ensure the electric antenna is extending and retracting properly.