I had this issue also with the pump handle. I used a #1 -3inch screwdriver. There are two screws inside the Shell that you have to take out also, so before removing screws take the barrels out first. Use a pair of pliers to pull each of the three barrel pieces out. Then you have to take off the Shell that is clipped in. Use a couple small flat tip screw drivers to push in between where the clips hold to the main part of the gun then pull the Shell little by little off. That's the easy part. Now after unscrewing all the little screws carefully without stripping them, open the gun from the bottom. The clear top will stop you from fully opening the gun so take your screw driver and push the clear circular tabs up from inside of the gun up. Pull the clear part, from the back, up and rotate it forward to come off. After I got to this part I noticed that the issue was not in the pump handle. Double check the pump handle. Hopefully that is all you have an issue with. My problem was in the piston part itself. If...