2. Then you need to take the whole power unit out of the car and take the back portion or plastic cover of  the power unit apart.  This consists of 4 screws.
 

3. After the plastic cover is off you will see what looks like a plastic saw blade, this is a switch, grab a hold of it and pull it out.  Then unscrew the plastic plate that this switch is mounted in, remove them and flip the plate out of the way, or to the side.
 

4. Then pull out the little gear that is off to the side of the large gear.  The pull out the large gear in the center, this is the gear that grabs the cable that raises and lowers the antenna mast.  Clean out all the grease in this area where the cable and the gear mate.
 

5. Look for the pin ( which part one can't buy ) that acts as a guide, it looks like a roller type pin, it is where the mast cable comes into that gear area ( the pin doesn't roll, it is a solid guide ). In the roller photo above, the pin is not worn and is to display what a good one looks like.  This pin/guide keeps the antenna cable close to that gear that you just took out.  There will be a grove worn in it from the cable going by it or the mast going in and out. There are two way below to fix this as there is no new part available.
 

1. Take a pliers and pull the pin out and turn it so the worn section of the pin is now facing away from the main gear and put it back in.  This can only be done if that pin is not rusted.  If the pin is rusted then do step 2 below.
 

2. You need to buy some epoxy ( permatex quick set auto Epoxy QM-50A at an auto supply store or equivalent ) and build up this pin/guide so that the cable will be closer to the gear that raises and lowers the mast.  The clicking sound is caused from the cable slipping, being to far from the gear that raises and lowers the mast.  You will have to then and/grind/dremal, the overage of the epoxy, because to much is not good either.  Once this is done the cable will no longer slip by the gear and make that noise.