Hmm, not so sure, I think I might have got a bad ‘un ?. It won’t pump above about 500 psi, the non return valve doesn’t seem to be non returning. I’ve changed the spring and o ring, cleaned everything up and it’s still the same. Every downwards pump it just bounces back up again if there’s any resistance. I’ve had enough messing about with it now, asked for a replacement and we’ll see what happens? Jury’s out atm.