Lens replacement
is not that hard to do. After the old lens is removed you need to obtain a new piece from a commercial plastics supply house, they should be able to cut, rout and bevel the replacement lens from the old sample or from a pattern. Make sure to leave about 1/8" gap between the end of the lens and the frame. They will also probably sell the caulking silicone used, GE Ultraglaze II,black. After cleaning up all old residue, mask off areas as necessary and apply new silicone to both hatch frame and underside of lens trying not to trap any air bubbles. Use the tip of an old spoon to feather the silicone on top of the lens and remove excess when cured. Good luck.