It's the shaft that runs the antennea up and down. Here's how to replace it.
- Remove the crank handle (allen wrench holds it to the shaft)
- Remove the spring and directional plate
- On the roof, pull the clips and pins that hold the antenna arms to the base
- Slide the antenna aft, making sure to clear the gear out of the base
- Remove the black plastic plug in the top of the base
- Using needle nose pliers, remove the shaft through the hole under the black plastic plug
- Seeing that it's broken, you should get up there and look down the hole to be sure you get all the pieces
If you do this once a year to lube the shaft and gear (silicon grease), you'll never have the problem again.