Finally. fast diagnosis...good price
 

When hitting brake, lamp failure light came on my 1998 E300D. Right rear brakelight out. Replaced bulb....short time later, warning light came on again...played with bulb and saw small spark near base of bulb on metal plate that bulbs go into. Plate became very hot. Called local dealer. Parts dept knew right away the plate was cracked...drove over....complete tail light assembly replaced in three minutes, (four nuts). Cost.....$46. Beautiful complete unit...couldn't believe the low price.( BMW tail light assembly for 540i $190.)
For the first time in a long time with Mercedes.....fast accurate diagnosis, fast fix....low price.
Final thought for those with the current E-class...recurrent shorts and bulb failures....replace the whole unit. Clever metal plate connects wiring to bulb sockets....crack in plate..easy replacement.

Diagnosis is easy when a part is built so poorly that one sees the problem every day.

Back when they built real assemblies it took twenty years or more before corrosion caused such intermittants.

I am quite sure, general quality has suffered greatly in the past years.
Richard