Trying to troubleshoot what is going on with our filter gauge. We replaced it about six months ago because it wasn't registering. It worked normally until about 6 weeks ago it kept registering lower and lower until it stopped on zero and would never move. We cleaned the cartridge filters and still no gauge movement so figured the gauge had gone bad again. Replaced the gauge today and it still won't register. It is a bottom mount pressure gauge. Is there something I can look for to see if the gauge is engaging with the filters or not? Or any other ideas why nothing is registering ? Thanks!