whats wrong with my headlight

Chrysler saw fit to use conductors barely of sufficient size to carry lighting load when car was new. You will find the eight inch grounding conductor serving headlights is one wire size smaller than the feeds to each filament. With age, that ground connection degrades from chasses, body weld, and fastener corrosion. The headlight bulbs on the shelf today draw more amps than the ones original to a forty year old car. So just using today’s lowest draw bulbs, the circuit is under sized.

By improving equipment grounds to lighting, the lights will receive closet to design current flow, and lights will burn brighter. The next upgrade step is to run headlight supply via two relays triggered from headlight switch, and powering lights from battery or power lug on alternator.

There is some disagreement to the correctness powering from alternator, but Dan Stern Lighting instructs that this is acceptable practice for these vintage Chrysler electrical systems.

I have made this upgrade on my 67 Dart, and the headlights are considerably brighter using run of the mill halogen sealed beams, and a huge load has been removed from the headlight switch. Next step will be to upgrade my bulbs.

All that being said, I agree that the filament has most likely broken, than it has temporarily healed its self from a bump, and will soon fail for good. This has happened several times to me over the years.