It's possible somebody in the past has mixed up the wiring where the wrong prong of the 3-pin headlight connector is attached to ground on at least one side. When you're looking at the connector plug on the back side of the headlight, the center pin is NOT the ground. I don't remember offhand which one of the side connectors is, but it's pretty easy to figure out.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!