Originally Posted by zzANGUISHzz
The end cap is on correctly.
This is how I fixed my leak.
While orienting the marker in a safe direction. Air up the marker with a full bottle, "this process will empty your tank" look at your bolt cap, you will see two allen threaded holes, if you will, below the cap. WHile the marker is leaking slowly back these thread caps out of the marker. These two threaded areas are referred to as the solenoid inserts.
I bought my NXT used. What the original problem was is that the noid inserts were swapped in the incorrect positions. If you are looking at your cap, barrel oriented down range safely, the noid insert that has a screen attached to it on the end should be screwed into the left port below the bold cap. The insert without the screen will be inserted on the right side. Hope this helps.
Make sure to reference the entire thread there is alot of good info in here.