Originally Posted by Ricky Bobby

Well if you already swapped bulbs around and the same side fails to light up, then its not an issue with the bulbs, its your ballast. No need to worry about high voltage, just don't turn the ballasts on (aka don't turn on your headlights) without the socket being connected to your xenon bulb (or you'll see sparks fly out of the socket lol!)

You've basically already narrowed it down to the ballasts, looks like you might need a spare Hella Gen III (pre-facelift) ballast.