I think my Polaris 480 has a broken back-up valve too, but I don't want to spend the $50 if it really isn't broken. The valve sprays continuously, and I know it is supposed to only spray for about 30 seconds at a time. Thus, it never ever backs up anymore. My problem is that I can't get that outer cover to come apart to see if it is part #45 or #46! Any ideas that would keep it from breaking while opening of the back-up valve that is too tight?