Classic valve leaking

[verypoormagowner]

My classic valve lvl 10 automag has suddenly started leaking. Im nopt one hundred percent where the leaking is coming from but im pretty sure its leaking out the on/off. But when i hold down the trigger it doesnt leak which i thought was a sign that its not the on/off. The manual says to change the orings but they looked fine an di oiled them. I dont have any replacements but im pretty sure there ok. The gun shoots fine but theres always an audible hiss.

[Dayspring]

Check and replace the orings in the powertube & where the two valve halves screw together.

[Raven4000SX]

Dayspring,
he says that when he hold the trigger back the leak stops. It's definitely the powertube o-ring.

[verypoormagowner]

ill replace the pt oring and then post again