So I attempted to open the inground pool this year (always had the pool comp do it) The problem I have is when I set the skimmer/main drain valve to center my pressure goes to zero. If I set it to main drain or skimmer the pressure is fine, Also when I set the valve center for stair jets/wall jets nothing comes out of either jets and the pressure goes up to 30psi. But if I set it to either wall or stairs it works, but all jets work not the one I am trying isolate.....I suspect an airlock but I am not sure....any help would be appreciated