That looks like it's pretty good shape; they put the "schmutz" (electrical connection grease) on it. The set screw looks rusted but that's not an issue. I think you'll be good with the pigtail. All seven of my pins were rusted out and the black auxialiary wire that powers the batter charger was actually broken off inside. That's why I replaced it.

Yeah, all the lights including the marker work when I hook it up. I just have to have the mechanic who installed the brake controller to re-examine it because it was not making a connection but I think that had to do more with something on his end not with the pigtail.