I need some help guys. I've got a problem with the manifold that came with my ak900. The low side valve will not open. What I mean is the valve and handle will turn but I can't Blow thru the manifold... its like its plugged. I took the knob off and then the brass peice with the o ring on it. I turned the valve that is in the manifold but this doesn't seem to make a diiferance either.

Any ideas? I hope this makes sense.