Headlight Issues

I'd swap the seal beams to see if it's the bulb or wiring.
If condition still existed, I'd clean the ground connection at the rad support beside the rad and/or supply an independent ground to the seal beams, middle? contact I believe .
If the electricity can't find a ground down at the bulb, it often seeks the only ground it can, back up the harness hi-beam wire and thru the hi-beam indicator on the dash.
Cheers