I have a three-year old Autotrol 255 with a 440 timer. It was working fine until a week ago. Now, when the regeneration process runs, it sounds like it's running through the process okay, but it doesn't draw any brine AND it also doesn't send any water to the brine tank during the fast rinse/refill step. Following the manual, I've replaced the check valve (there was no ball in the original one!), I've cleaned the injector and injector screen. Is there one failed item that can cause both of these symptoms? Any advice would be appreciated... Thanks!