Testing some Vintage Christmas Lights

A look at some old C7 Christmas lights I bought at a flea market, got everything seen for I think $5. There was a whole box of lights, I regret not buying the whole box because these are becoming harder and harder to find. I'm a little irritated because I was told they all work, and one set does not. Hopefully its just a case of 'when one goes out, they all go out', though I wouldn't think this set would be one of that kind. Update: The lights have since been repaired and put into service.