Stop in for a cup of coffee

How the hell did that get melted anyhow? Corrosion?
I'm going to guess it was the time the headlight wires had chafed enough to ground on the edged of the buckets. really had me puzzled as the relay was already installed with fuses. Fuses didn't blow, but the lights kept going out. Low beams the worst. I stopped a service plaza on the NJT got some bulbs but that wasn't the problem!