I’ve often found that after several years use my battery lights become unreliable and may dim or go out even with good batteries and clean contacts.
I’ve decided that this is because with all the banging and bumping they get on Cambridge roads and paths the spring contacts that hold the batteries become weakened and no longer make good contact. In the past I’ve tried ‘bending’ such contacts, but this risks breaking things and does not provide a permanent solution.
I’ve just been told of another method: cut up a small piece of plastic or rubber foam and squeeze pieces of it behind the contacts to give them an extra ‘push’ to make good electrical connection.
I’ll be using this method on both our CatEye front lights that have started to give trouble.