[CaptainForce]

I think the OP is speaking of the spin on cannister primary filter on the engine and not a Raycor or maybe I'm wrong. You'd think that people would consider the "primary" filter as the first filter that the fuel encounters after leaving the fuel tank, but the term seems to be referring to the filter mounted on the engine and not the Raycor. Of course, either way it could be the O-ring and air must be getting in. Take care and joy, Aythya crew