Hi , like most people , my lamps on my newly purchased ml500 are fogged . Yes they can be polished but it's never as good a new shiny lamps . So Looking at new units , the only difference I can see between xenon and halogen is thebalast plugged in at the bottom ? Can I just buy a new unit , swap the bulbs and the ballast over , and job done? I've not tried to take it apart yet , so you may tell me the xenon unit is sealed and cannot be taken apart or something . I can't find OEM xenon units for less than 500 each which is just insane . Help please !