The power antenna motor continues to run after mast extension. At first, it sounded like gears grinding until I pulled out the mast to full extension,(it stops about 3 inches shy of fully extended) but then I needed to push it back in slightly to get it to retract. At any rate, at either fully open or closed, I can hear the motor still running. Before I pull apart the trunk to get at the assembly, should I expect to have to replace the mast, the motor relay, or what?

Just the mast. The bottom of the mast has a plastic toothed cord which may have broken off. If that is indeed the case, you will have to putt the motor housing apart (watch out for springs) and remove the remaining piece of plastic.

The new mast gets inserted from outside of the fender. When it is pushed down as far as it goes, turn the radio off and let the motor pull down the plastic. It helps to have someone turn the radio on and off while you are trying to get the mast to seat in the motor drive.

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

Thank you. When the car comes home next week I'll give it a shot.