Not an expert on the matter but does it have something to do with the switching cycle speed of the lamp matrix? LEDs would be much more affected by the switching cycle than incandescent lights as they will turn on and off almost instantly. If it is the problem there may be a simple patch for the game ROM to correct it? Maybe a more technical person can answer that question. Check out this link while you wait with an interesting product to correct flicker.
http://ledocd.comuv.com/ Found it while investigating LEDs myself. Don't know if any one has tried it.
