the switches have very small bulbs in them which just twist lock in. iirc all switches have two bulbs - one for illumination - one for 'on'. just flip out the switch carefully with a flat bladed screw driver and check. they just look like two small plastic discs with slots in for a screw driver. unlock it and shake it out.
try Nissan for the bulbs as i don't think they are too bad for small items like this, and they should know which one you will need. other than nissan, try an electronics shop - like Maplins or even ultra LEDs.
