Help! I recently stopped in at my local MB dealership with my 2007 ML63 AMG to correct low tire pressure and what I expected to be a "quick" low beam bulb headlight replacement. I was told on this model, it involves an appt for the mechanic to check whether the bulb, igniter, ballast, or possibly an electrical issue is causing the problem, and no quick way to tell if this HID bulb is burned out. Apparently the bulb alone costs over $300! My son is an entry level mechanic for a Toyota dealership, and has done extensive work on his 93 Supra over the past couple years, including some electrical problems. I would love to have him do the diagnostic work and replace whatever is wrong, but where is any info on how to go about it? I don't want a $500 + bill for a headlight bulb replacement if it can be avoided! I remember thinking paying $100+ for a xenon high beam bulb was ridiculous! Any helpful info would be greatly appreciated.