IMHO (I have a little experience in servicing electronc equipment), John in Kansas has come up with an answer to Susan's problem: corrosion, often invisible, at the battery terminals.

Scare the battery contact AND the mating battery connector with some wire wool. Then wipe a thin film of Vaseline over the mating parts.

This has cured a great many 'battery faults' on equipment I've have had to repair.

Good luck.

John