I had this exact same problem with my 97 SL500. What I noticed was the connecting socket even though pluged in needed to be pushed in a bit further. I just applied preasure and the light brightened up again. This happend multiple time so what I did was take one of my wifes dental files and pushed it into the light socket(believe me the power was off) and did a light sanding. This seemed to clean the contacts and it never had the problem again. I know you may not have access to a dental file so you may be able to find something else to use. Hope this helps.