In my opinion the issue is that the bulbs sometimes cause too much heat in the bucket. You might consider LED’s from the UK source they are just like an H4 in length and width and it seems in light pattern.
@Carlos G posted:I'd be curious as to what caused the meltdown. The area where a Spyder's headlight bucket sits in, is pretty tight.
Do both sides look like this?
Heat at an electrical connection is always the result of resistance. A wire in a conduit will almost never burn up (unless there's a dead short somewhere). We see stuff like this ALL the time, and it's almost always the result of a connection being loose or poor. The only time it's not is when it's in a very hot environment (an oven or a burner). Ray may be onto something, but my money is on the connection itself.
Mike's suggestion of dielectric grease is a good one. I'd also pinch the female connector (if I could) to make sure it's super-tight on the bulb terminal flags.
Well I may be completely off Stan 
This was found on one light only. Replaced and greased. If it happens again I’ll try the LEDs.
Sounds like a solid plan
@IaM-Ray posted:Well I may be completely off Stan
Or you might be right. I'm just saying that the place to start is with the connection.
I'm pretty sure this connector got wet. But the H4 bulbs do draw more current than the LEDs. I drilled a 1/4" hole in the bottom of each headlight bucket, in a Spyder they drain into the frunk, unlike a Speedster. You could even get the VW headlight drain tubes and maybe extend them out. Or don't drive in the rain(or wash your car!).
I had a meltdown like that in one of my relays. The spade connector had shifted in the housing when I pressed it on, so I got arcing when I put the lights on. looked basically like these pics.
This was definitely due to moisture. The headlight that went bad showed signs of standing water. I drilled holes in both headlight buckets and replaced both connectors even though the other one wasn’t bad. Thank. Danny.