I know this is a very old thread but I fixed this problem using aluminum foil and a plastic washer. There are two small pins on the bottom of the battery chamber. Wrap a single layer of foil around the neg side if 6 volt battery and make contact with the two pins when putting the battery into the chamber. With scissors cut a rubber washer into a small rectangle to fit into the space on the back door opposite the battery. This will push the battery to make contact with the positive pin and hold it in place. It worked.