I just picked up a SATA JET at an auction. It's an older top feed model. I don't have a cup for it yet so I am not sure if it works ok or not. When I hooked up the air to it the trigger worked fine but a small amount of air is running thru the cap ( or somewhere) all the time. Is this normal? I am used to painting with a Binks 2000 and there is no air all the time on that one.