I am selling a T9.1 in the Classifieds for a family member. It is advertised here and on Facebook Paintball pages along with the Guy's other kit in the thread titled 'Selling Up'. The T9.1 appears to have an issue. We put it together at the weekend just gone to try it out. The T9.1 fires as expected but the the gas cartdridge then dumps all it's gas from somewhere inside the marker. Any ideas on how to check it out or where to start looking will be gratefully received. Tghanks in advance.