O2 & Brake Sensor lights not working...
 

These are the only two idiot lights not working in my dash (unless there is a Check Engine light that I am not aware of). What could it be besides bad bulbs?

How hard is it to replace these bulbs?

Make two hooks out of dry cleaning shop hangers. About 10" long with finger grips at one end and ~5mm bent ends at the other. Squeeze the hooks between the dash bump and the gauge cluster at either end about mid height. When you can, turn the hooks inward to grab the gauge cluster. Now draw it out.

I've not done this in a pre 86 126 so I don't know if the steering wheel is out far enough to let you work on the cluster. The 86-up have telescoping steering you get that much more room. It'll be easy to identify which bulb belongs to which warning light.

FWIW, these cars have an inductive speedo drive so there isn't a big greasy clip to wrestle with at the back of the cluster. The oil pressure gague is electric so there isn't a an oil line crack and leak oil on your shoe. Though I have more faith in mechanical gauges.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD