the factory lenses are not glued in, the acrylic is heat folded over the light frame on the inside. this creates a water resistant enclosure. the folded lip can either be taken off with a 'hot knife' or with a dremel tool. i have always found the hot knife to work better, but you do have to be careful ... and go slow so the knife doesn't slip and hit the visible part of the lens. you have to cut off the lip flush with the frame so you can see the two pieces side by side ... and you have to go all the way around each of the 3 lenses in each frame.
patience is required