Now this is the High Volatage market with the extra grip in the front, while the manuals are for the one with only a trigger frame. In other words, I bought it at Walmart. It's a great marker, but it's leaking CO2 out near the front, by the cup seal. I think it's called the LVC? How do I tell if a cup seal is bad and how can I remove the front grip to check out those components? Is it probably a broken O-ring?