Hi steelclock, Well I pulled out the cluster and replaced every 1.2 watt lamp I could find that iluuminates the back of the dials with new ones. Whilst I had it off, I also cleaned with contact cleaner the shaft that runs through the dimmer/reset switch. As I said earlier, this is a solid state affair so there are no wire contacts to clean and as the dealer here wanted over $120 for this piece, I though this a little expensive just to troubleshoot. I also noted the previous owner had soldered a parallel lamp installation to the red battery warning lamp and used a blank red annunciator window at the far right of the lower strip. This I removed as I dont really need 2 red lights to tell me I have a battery faulty. I reassembled the whole lot and waited until it got dark ! Wierd thing is, it is still the same. I am comparing it with my 190 which has the same 1.2 lamps and is a lot brighter, perhaps this is normal for the 500SEL. I don't know. I found a dimmer switch in the scrapyard during a recent visit but is only has 2 contacts on the back and is the old wire wound one and clearly designed to fit another auto. Perhaps I ought to accept it as it is ?