Place the pistol on safe.

Press the magazine release button on the left side and remove the magazine.

Slide the grip to the rear, exposing the CO2 port.

Make sure the CO2 screw is fully unscrewed.

Add a drop to the tip of the CO2 cylinder and insert. Screw in until the CO2 is pierced and sealed. Do not overtighten.

Load the magazine by pulling the follower down until it locks into place.

You’ll notice a nub that protrudes from the bottom of the magazine, take care not to bump this while loading BBs.

Tilt the magazine downward and insert 20 BBs.

Place your finger over the end of the magazine and pull the protruding nub toward you.

The magazine can now be inserted, press until it clicks. Your pistol is now ready to fire.

Align the front sight in the rear slot with the target sitting on top. The sights are fixed, so if point of impact differs from the point of aim, try cleaning the barrel and/or switching brand of BBs to get the best accuracy.

Once you have the gun apart you will just need to take the old seal assembly out and replace it with the new seal valve that was sent to you. Putting it back together is tricky because you have to do it the same way you disassembled it. (I attached a picture of the gun disassembled in the disassembly FAQ so you can see the parts as well)

If that seams too complex and you don't feel like you can repair it, you can try and replace the seal inside the old assembly by unscrewing the inside by the seal. I attached a picture of what i'm talking about if that didn't make sense. That will require you to unscrew the new seal out of the assembly I sent you.