Pneumatic nail gun oil leak how to repair?

Base disassembled, the piston pulled out, the outer sleeve removed (that is, the silver-white put rivets), you back to see there is a 6 angle nut, remove all, and then remove the sealing cover (out of the nail rod where the nut), the spindle from the back to pull out the top of the rubber ring replaced, and then fully loaded up a few OK, don't forget to refuel me. Quite complicated, basically the nail gun all dismantled. There is a certain degree of difficulty, you can try