I have replied on the other forum Danny.
Im no expert, I just know the right people to ask if I cant fix it
chances are you are over lubing the poppit, and its sticking forward. If the gun used to work fine, and it doesnt now, it probably means that it isnt the actual poppit at fault, its something else, and thats my guess.
When lubing something, you are only really lubing the parts that touch each other (oo-er missus!) like predominantly o-rings, and a little bit on the bolt and bolt tip. Just get a little bit on your pinky, and spread a thin coat on each o-ring, the bolt (or even a little on the big spring) and the bolt tip.
Put your pressure up to just under 200.
Edit: also, for resetting the poppit, screw the back cap all the way in tightly to make sure that the poppit face is properly sealing. If this stops the leak, but the leak returns once you unscrew the back cap to your proper velocity you should check your poppit face for damage. There should be no lube on the poppit face, or in the hole in the side of the poppit. Only a slight amount of lube should be on the o-ring.
Hope that made sense and Im not waffling too much?