Hello! I have two ceiling light fixtures that mostly don't work. That is, 95% of the time, if you flip the wall switch they don't turn on. It's not the bulbs; I've tried changing them. But once in a while, they do work. Once on, they will stay on. But if you turn off, then immediately back on, will not work. They are independent of each other, as in when one comes on the other remains off. This happened to one fixture first, then the other many months later. These two happen to be on the same circuit and I have two additional light fixtures of the same make on different circuits that work fine. The house was built in the late 70's, and it's in California, and I've been in it 5 years. This seems like a bizarre problem. Is this a wiring issue or a light fixture issue? How to fix? Get an electrician? Thank you!