Ah, I knew I would find it! The F1 Illustrator manual, complete with troubleshooting guide: https://www.vintagerex.com/pics/gunpi...1%20Manual.pdf
The double-feeding is due to the retention wire/spring being too loose. The CO2 leak could be from the valve pin not being in the correct position in the front section (the section where you have the star-shaped washer). Read through it, it should help. I have a loaded F1 for sale in the MCB members section, complete with a few barrels and a regulator, PLUS a loaded parts box.
Oh, and Thank You for your service to our country. God Speed and keep your head and rump down!