Since the entire unit is out of the car, making it harder to work on, place the motor on a workbench with a vise to hold it down. Extend the antenna as far as it will go.
Take a pair of conventional pliers and place it just under the antenna tip. Tap the pliers with a hammer. The sleeve will then slowly come out of the base.

It is usually corrosion around the sleeve that causes the antenna to stop retracting. Take note when you pull the plastic cable out of the motor housing, the grooves must go in on the same side with the new antenna.

BTW, mount the antenna motor back in the car before putting on the new antenna. Have the radio on, so that when you get the white plastic started, all you have to do is turn the radio off to draw it down. A helper is nice to have.

Klaus
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Volvoless. Sold the R. There is now a void...