---MIKE--- wrote:
My bathroom light consists of a 12" ring with an 8" ring inside. At
times it won't come on and at other times it works just fine. When it
fails, a heat lamp on the same switch does work. I have replaced both
rings but that doesn't help. I don't see a ballast or starter but I
haven't looked inside the fixture. What could the problem be?

Sometimes a florescent fixture acts like this because of a crappy ground.

May not be your problem, but it's cheap to check.