OK guys, so I just got my Size Doctor. Tried it out today to see how it works - looks like it's going to be a sturdy bit of kit.
The valve though doesn't close for me either - so I put the black adaptor first, then grey bulb, then pump and my glans comes in - all fine till that point. Then you have to remove the grey bulb and black adaptor - when you do all the air goes out via the small black pin (the one with the orange o-ring on it) because it's in the outward position and the action of pulling the black adaptor away from the head pulls on this pin. So only way is to not take off the black adaptor but then vacuum gets lower over a few minutes. Any ideas?
I did just check the vid earlier in this thread, and it seems from seeing it that the black pin should be able to be in the loose position even after removing the pump without air escaping, and then you use the clip to keep it in place so that it doesn't go in too far, and then to release the air you push the black pin in? If so then that's the opposite of what I have where, in order to keep air in the chamber the pin has to be pushed in, and pull it outwards and it releases air....
Cheers