Oh, i thought it was a motorcycle trailer but its a trailer with a pop up car carrier top bolted down on the trailer. Not a bad idea but expensive with
Yes there is a small Oring in the power tube. Sounds like your problem if the leak stops when you hold the trigger in.
So i was playimg today, ball gets stuck on a break in the hopper, big gush down the barrel. I di a full clean amd rebuild, still major leak down barrel.