Definitely doesn't hurt, but be prepared to get covered in grease. Also make sure that you take notes as to how it all goes together, as well as being careful so that the mast cord doesn't go flying (it gets coiled up around the spindle when the antenna is retracted, so much like a whipper snipper or mower starter cord it tends to "release" itself very easily once you remove the housing. Had to do this on the ex's SXV20 antenna (hers had stripped some of the teeth so you could "assist" the mast up and down through the stripped bits but otherwise it would just sit there and grind away non-stop until it timed out.
Potentially, if the motor is dead but everything else is fine you might be able to swap in the motor from a sedan one and keep the wagon housing, as sedans are much more common.