I saw this on a list of things that eventually need to be replaced. As far as I know this is still the original one so It's been in there for a minimum of 5 years since we moved in and I have no idea how old it is before that. Is there a way to see if its fully working? The Polaris does back up every once in a while so it's doing something, but how do I know if it's working fully or if its starting to degrade?