You could also have a cold solder joint on the light board or it could even possibly be plugged in wrong. You would be suprised at how many things could be the issue since it's probably had a ton of inexperienced people fixing/working on it in it's lifetime...There are also 2 different connectors and boards under there. One for the regular 6v inserts and 1 for the flashers. I'm leaning to a bad connection on the insert board...