Left headlight of s2k retro won't turn on

I just recently ran into a problem with my retro. I had someone make me a wiring harness years ago from this forum for my s2k retro with toyota ballasts. For some reason, only the right side is lighting up, left side won't light up at all.

When I use one of those power checker things, where I plug one end into the battery's positive and the other I touch to see if the light goes on, I get a very bright light on all the negative connections on each ballast, but I get weak lights on the positive connections. The positive connection on the battery is nice and tight, and I tightened all the connections on ballasts.

I even checked the wire going from the right ballast (from the relay) going to the left headlight's ballast, and the wire has no cracks or anything. Any idea what I should do next? Thanks.

ballast may have went

try the swapping the right side headlight's ballast on the left ballast. See if that will make it light up.

If power going to the ballast seems to be good, then that's more than likely your problem. Unless something is goofy with the wiring harness your buddy made

^+1. You could also try putting some dielectric grease in your plug connections.

Seems like the left sided ballast died or something. The positive connection piece completely came off somehow. How do I test if the ballast is working or not before I deem it dead and swap it out?

got a test light? or a DVOM?

I used a test light and stuck it on the positive part, no light. There's barely anything left on it to test it though. Negative turns on though as it's connected directly to ground.