The valve after removal from the HPFP. Note its collar is not sitting flush where it is when installed. It is not a molded part of the valve, and comes off pretty much all by itself. Also note the blue O-ring. I did not replace it but it was visibly worn. If someone with the needed background can figure out the right part to buy could let us know here in the forum... also note the small unknown-material ring immediately below the topmost O-ring. Presume that it's fragile! See later shots.