Just for drill, you might try replacing all the fuses - sometimes they can develop a hairline crack and look fine, (and occasionally even check OK with a meter), but heat and vibration open them up. You might also consider checking the battery ground wire and other grounds. On my 87 300E, the instruments and brake lights are on the same fuse. When it got a hairline crack, the same thing happened. It is a cheap starting point, anyway.
BTW, you list your location as soCal. Check out the thread in 'Open Discussion' on the Mercedes Shop meeting in SoCal, if you are interested.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E