These four ft. fluorescent light fixtures have a decorative flat panel. They have 2" blue glass around the edge and the rest is 4 white plastic rectangles and it is all joined by what looks like lead seams. I broke one cover. Is there anyway to find a replacement for it since we have all four lights are the same? These light fixtures are old, approx. 30 years old. Here is the information I located inside the light. (Underwriters Laboratory fluoresant fixture, Issue No. C-143,913 118 volts 60 Hz E76333). PLEASE CAN ANYONE HELP ME!