Well I think the problem is the connector that hits the center peg on the bulb is some cheap SPRING steel. I think it fatigues, the clue was the light seems to work initially but not after a few stops, so maybe a little heat from a few stops and the spring is gone. So I push that center tab against the bulb. At this point the black cover is always off so I have good access to the bulb. Concerning grounding - I think it is some kind of pass through circuit as I figured the outside connector for the bulb was ground but when i clip a ground wire on to that it just blows the 10AMP fuse.

The solution would probably be to get the new piece that holds the bulb, No idea if that's available from volvo. I tend to avoid used parts as I imagine i have one of the lower mileage 850s so used parts most likely are worse than what I have.