Here are the ground points for the front lighting circuits:
Pull the bolts, wire brush the threads and underside of the bolt head. Clean both sides of the wire terminals to bright copper. Use a tap and chase the female threads in the weld nuts that the bolts thread into. Also, clean the frame in the immediate area around the weld nut to white metal.
Reconnect the ground wires and make the bolts up nice and tight. Test the associated circuits. If they are okay, apply a light coat of Rust- Oleum Rust Reformer to the raw metal.