Pops, the rear shelf brake light assembly comes apart from inside the car. As JoeR says carefully pry the tabs on either side of the colored housing and slide off. Once you've got that done the rest is pretty obvious. You will be able to remove and straighten the rubber seal ... clean that section of the rear window while it's accessible. Be sure to use the proper wattage replacement lamp ... Osram Sylvania as I recall.

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Fred Hoelzle