In the case of the 100 (as opposed to the generic 1xx series), the display cable seems not to be a common source of trouble. However, the -21V supply that biases the LCD does seem to be a weak spot. More specifically, the electrolytic cap across that supply output (those darned electrolytics, again!) seems to develop enough leakage that the converter has trouble starting up. Sometimes, just leaving it on for a long period of time will fix it (at least temporarily).

By all means first check for loose cables, zap the pram, etc. But if those standard operations don't fix it, you may want to look into the dead LCD bias theory. Somewhere around here I have notes identifying which pin to check, but if you just measure all of them and don't find anything that measures around minus 21V, then that's your problem.