Digging this thread up, but I figure its relevant to the topic. I am going through a Baby Pac project and a ton of lights were out. I replaced them with LEDs. A few of the lights under the playfield ghost, but only a few. The rest work just fine. They also don't light at all. On one of these, an incandescent bulb in that socket stays lit all of the time. I am assuming the diode on those lights need to be replaced?

I originally thought that too, but it's not in pairs like I've seen addressed before. It's literally a few random lights in random spots. Not that I don't believe your answer, just wanted to be clearer about what I'm seeing

Ah. I see. I blindly assumed the pairs were next to each other. I don't know why I didn't think to go to Pinwiki. Used it a million times.

After hearing the horror stories, I keep the game off when I switch lights out. Looking at the chart link above, your answer looks like it might be my issue.