The Part number for a new mast is 9494389. The new mast comes with instructions. Using two people makes the change over easy, one in the car turning the radio on and off and the other at the mast. To start the replacement, antenna down, use a 16mm wrench to loosen and remove the hold down nut circled in yellow.

         Once the nut is off, turn the radio on and gently pull up on the mast until all of the white plastic gearing is free of the car (note the direction the gearing is facing). Examine the end of the white gearing you just removed, it should have a slight taper, compare it to the new one. If the white taper is not there and the plastic gearing looks like it is broken, then you will have to take the motor apart to remove the rest of the antenna. For this repair we are saying the whole antenna came out.

         Take the new antenna mast and insert the gearing down into the hole until it bottoms out. This is tricky, before inserting the gearing try to straighten the end so it will be grabbed by the motor gears. You might try turning the white gearing so it faces the rear of the car, this might help it to drop down that last hard to get 1 " , then turn the gears back to the front. Turn the radio off, if you are lined up the gears will be pulled into the housing. You might feel the motor turning and rubbing on the white gearing but not feel it being pulled down, try backing off a little then pushing down, keep fiddling with it and it will grab. Once the gearing begins to retract, guide the mast into the housing. After the motor stops retracting, put the 16mm nut back on and tighten, if the mast wasn't pulled all the way down, push it down now. Cycle the radio on and off a few times and you should be good to go.