I'm having a little bit of a problem with the left headlight on my 1992 190E. I noticed that it was a little dim, so I took it out and looked at it. When I put it back in it was back to the normal brightness. After about a week it went dim again. So I figured it must be something with the contacts. I sprayed some contact cleaner on the prongs of the bulb. It worked fine for about two months, but now it's dim again. Does anyone know how I can fix this problem? Thanks.