Sometimes my mothers car won't start.

What is your question?

They had a rebuild starter put in and it started fine for awhile. Now it doesn't start again so they took the starter out and took it back to Advanced Auto and they tested it and said it was fine. Could there be a dead spot on the starter that they wouldn't see when they tested it? Seems strange that it worked fine for a couple months and now it won't start again. Occasionally it will start and run for a couple days. Any suggestions would be appreciated. Thank you in advance.