Originally Posted by ta2maki
If you pull and hold the trigger down, that will depressurize the power tube o-rings. If the leaking stops, then you know the issue is within the powertube.
And if the leak doesn't stop, then start checking all the o-rings in your on/off assembly. If all else fails, take it all down, clean, and put back together. Sometimes little bits of debris or ptfe tape can cause those kinds of leaks too.