Some of you may be aware of my ongoing frustration with these things. Briefly I've had one that refused to close off and another that has leaked when in the open position. Time to investigate. I suspected that the issue was junk seals and it turned out I was correct. I carefully removed the crimped section of the aluminium operating knob so I could screw it off the body and remove the internal plunger. The seals were toast which was causing the leaking in the open position. Bearing in mind that