Steve wrote:

So far we have had two of about 20 or so to quit working. We figured
these two were burn't out even though they were only a year or two
old. But instead of throwing them out right away, I held onto them
for awhile or until we could bring them to a recycling or collection
place. Then, for some reason, I tried both of them in another fixture
for one last try. At my amazement, they both worked again! I just
rubbed off the end that goes into the socket really good with a
cleaning rag and that's all it took. So before you throw one out that
has quit working, give it a good rub on the end and give it a last
try! :-)
Steve

I've noticed something like that too, sometimes the bulb then works fine for
a long time, sometimes not. But it's certainly worth trying in any case.
Cleaning the contacts is also something worth trying with batteries and the
gear that uses them BTW.