Gosh, I've never heard that before, "everything worked fine until after the restoration" Unplug the light unit plug at the inner fender panel and use an ohm meter and start by verifying a circuit from that plug to the actual bulb socket, then verify it is actually the correct bulb, then verify the bulb actually is good by checking the bulb continuity with your ohm meter, then verify that you are getting voltage from the appropriate fuse when you turn that side on, then insure you have good ground by running a jumper wire from the light housing to ground. There is no easy answer, just have to go thru a logical process of elimination. And IF the car just came from the body shop look for a wad of butt connectors!