I have a new set of lenses but do I have to pull the whole corner piece which surrounds the lense, or am I missing something? Reason being is that I don't want to pull the corner body pieces due to the paint is covering the seam....If I remove them the paint will crack and not look as good.....thanks.

Yes the extension needs to come off to access the screws..The screws hold the trim on which holds in the lens....

If the paint has filled the joint area, try using a razor blade or some thin and sharp blade to carefully cut through the paint so it won't crack when you remove the corner piece.

How bad are the lenses, I would not pull the ext off, and risk a big crack/chip, at least try a plastic polish on the lenses first.