My 98 E320 developed a small hole (from arching) in the metal plate on the tail light assembley for the right rear brake light which created occassional lamp failure messages.
The temporary fix was to slightly turn the lamp socket so that it comes in contact with the good portion of the metal plate.
I might consider filling in the small hole with solder.
1998 Mercedes E320, 200K Miles
2001 Acura 3.2TL, 178K Miles
1992 Chevy Astro, 205K Miles