Not on my trucks but on my daughters car. Two are working intermittently and one of those quit altogether. Let me know about them when she was leaving for school. Will a liberal dose of contact cleaner possibly solve the problem?

 

Might, probably won't. Start looking for new ones.

 

I've had the plastic retainers on the back loosen up before too. Usually contact cleaner, some new dielectric grease and some crazy glue can get them working again. If all that fails then you may have to replace them. I had problems on my 95 and kept them going for an extra couple of years that way.