Damaged or Broken O-Ring
Okay, so the O-Ring is broken. Thankfully, it’s a ridiculously easy and cheap fix. All it takes is a quick trip to the hardware store or (if you can stand a couple extra days without using your SYNEK) click here to order a 5-Pack of O-Rings.
The dimensions for your new o-ring are 9/16" ID x 11/16" OD, and it fits right on the first lip of the CO2 tank. If your O-Ring is even slightly damaged, you will not be able to maintain enough pressure to pour beer.