W140 nightime illumination bulb replacement

Hello,

I was hoping to find some advice on replacing a few light bulbs for the night-time illumination for my 1996 S500 (W140 model):

1) The illumination in the headlights switch is not working, which is rather inconvenient 2) Same for the illumination of the two left hand side ventilation control knobs in the middle of the dashboard (the ones that regulate airflow to the left side ventilation opening and the one that regulates the left centre opening 3) Also, one of the electrical seat switches in the right hand back door is not lit up

Any advice on how the bulbs in these can be replaced would be very helpful.

Thanks,

Guido