I am a recent purchaser of a 1988 700 GLE sedan. The display where the heating and air-conditioning controls and the fan doesn't have any lights to illuminate it at night. should it?

if it should, is there a way to go in and replace a blown out bulb? it has an aftermarket radio installed by the owner. it has a light display, but might that have knocked the lights to the heating/ac controls above it?

i did a quick run through the 700/900 FAQ, but only find references to the instrument cluster lighting.

thanks for any help.