I've owned this model since new back in 1987(?). There are three AG3-style "fuse lamps" which backlight the display...one for the SEA equalizer, and two for the tuner and source selection portion of the display. If you are handy, you can open the unit up and access the bulbs. Their fuse-holder style sockets are soldered in to two small PCBs which are in back of the display. There are some plastic clip-pins you have to carefully undo, and some metal tangs which you have to straighten out to get the boards off. It's a bit tricky to explain but if you take your time you will see how it is attached. I think I got replacement bulbs at Digi-key, Parts Express, or possibly direct from Sylvania or Osram. One note: the lamps are run in series. In order to keep the display from going black when any one lamp burned out, the design has zener diodes in parallel with each lamp, such that current is still permitted to go past a blown lamp (albeit at slightly higher voltage drop.) The problem is that the power dissipated by the zener is pretty high and they tend to scorch the PCB that holds them.

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