I hope someone can give me some advice. We have four wall-mounted outdoor fixtures that we installed 4 or 5 years ago. Each takes two four-pin 13W spiral fluorescent bulbs. They're all equipped with a light sensor so they go on at dusk.

The two on either side of the garage work fine. The two on either side of our front door in a covered porch area fail consistently. The fixtures are all the same design, but the ones by the door have a slightly bigger enclosure. They worked okay for the first year or two, then they started failing. One or more of the bulbs in either fixture will fail to come on each night. I replaced the bulbs and at first that worked, but then the next night they went out again. I thought it might only happen in cold weather, but it happens in the summer too. It's getting worse, to the point where most nights now none of the four bulbs is working.

Here's the thing -- if I pull a bulb out and put it back in, it will work again. It may take a few tries, but I can usually get them to go on. It's just sort of a pain to do this to all four bulbs every night.

Any idea what's up? Is it worth having an electrician take a look at them, or should we start over with new fixtures? Thanks.