I am not sure what bulb they actually are, but they are not fuses. Usually those lights are not at fault, because they are used so little. I would be inclined to check the switches and other wiring, as those have a tendency to get finicky after 15 years or so.
Same problem, ive got a 92 Bonneville ssei, the visor lights wont work i don't think they've ever been used since ive had the car... The seat settings on the passenger side don't work either, so im thinking i have a big wiring problem..