Translating step 16
Place the other half of the body back onto the gun, making sure everything lines up. It's ok if the spring sticks out of the back for now.
While holding the body together firmly with one hand, use the other to push the spring inside. This may require separating the body slightly around the spring.
Once the spring is inside the body, grab the plunger tube guard and reinstall it with two of the short Phillips #0 screws.