I've got an 18yr little old lady cat who for a couple of years now can't go through the cat flap without banging on it with her paw for a few minutes before coming in or out. This is a problem because it's a sureflap so makes quite a loud swinging and banging noise every time it clicks back into place and she is waking up the whole house every morning at 5am or earlier doing it. Apart from completely locking it at night, which would be a last resort, any ideas how to stop it? She gets shut in the kitchen at night so I didn't really want to stop her from going outside if she wants to.