From the Haynes Manual:
Using pointy nose pliers, unscrew the antenna base securing ring (2 little cutouts in it either side of the antenna tip).
Here's where you may have a problem-switch on ignition, switch on radio, when antenna extends fully grasp it and pull it completely out of the assembly.Since your antenna is not functioning, I would guess you could grab hold of the top of the mast with pliers or grips and pull it out (that's what I've done in the past with other electrica antennae).
In boot, after switching off ignition, disconnect antenna electrical connections and the bolt or nut that secures it and lift out.
Installation is reverse of removal.
If you get it working, to get the mast back into the antenna, push the nylon part (with the teeth cutouts facing towards the round part on the base of the assembly) into the hole at the top until it goes no further. Switch on ignition and radio. When the motor stops running (it's trying to put the antenna up) switch off the ignition completely,the motor should run again, if you gently push down on the mast it should get gripped by the rack gearing and be pulled into the assembly. Then screw on the antenna base again.
Good luck.
GT
October 2010