Lights suddenly start working again

Yesterday my climate control lights began working after never working since i bought my 83 300D a year ago. The little buggers even brighten up when they are depressed, i was thrilled. However the temp control and hi/low sides dont work, or do these light up. Since my middle part lights up, is it just that the fiber optic cables arent hooked up to the sides? How easy can this be done? I will look in the Haynes manual, but not sure still.

[MBenzNL]

The European (non-airco) W123 heater systems have separate bulbs for the complete heater control panel and have one central bulb (behind the front plate of the console) for the fiber optic cables that run to the different switches (push-only) on the console.
None of the lights on a euro W123 are hard to replace.

greetingz,

My climate control lights will fade and eventually extinguish after a few hours of driving. They come back on if I turn the lights off and and restart the car.