I was able to ground out the bulb socket, and got that bulb to function properly. My expectation was, just grounding the one side would fix both. It doesn't. Weird. I was getting strange operation (wrong filament with turn sigs) due to the bulb finding ground in the parking lamp circuit. That isn't the first time I got nabbed by that kind of phenomenon, and I'm sure it won't be the last. I should have just fixed the ground issues first, then see what else is happening.

I think the ground problem is where 14 wires come into one bundle and bolt to the left fender. My fix is just to ground the ground wire for both sockets up front. I won't continue looking at this, since I have a list of other issues I need to knock off to get inspected. But figured I'd update the thread, to help others down the road.