Kebowers -- where were you two years ago?
I never thought that the costs of repairing the vehicle to be too much -- and $830 is a lot less than the cost of parts and effort thrown at the car during the 2 years of the problem-- and had I kept the car I would have done that repair. The car also was starting to get a slip in the transmission, had an oil seep that unfortionately dripped oil in such a manner that it burned on the engine and fouled the air inside the car, it needed a modicum of body work, a new soft top, the wheels were starting to peel clear coat ... etc. It was time for someone more enthusiastic to take it over (and I hope that happens).
I think you hit the problem on the head -- the problem should have occurred at all speeds and didn't and that is why no one could find it.
I do believe you that the newer SL's have costs that are much more and that was one reason I did not look for a newer MB (had thought of going to a CLK cab -- very nice cars).
I am still reading posts and consider myself an MB enthusiast. I have some accessories that I will probably offer on ebay next spring (when I clean the garage).
To all of you that have thought about this problem and offered solutions or commiseration - THANKS -- Keep those beautiful SL's of yours running strong!