I can't get my trigger on my Iwata HP-BC plus to spring back up after I depress the trigger. It will come back up slightly, but it won't pop back up to shut the paint/air flow completely. This is especially maddening when I am painting spots on a fish mount. I am an experienced taxidermist, so I DO clean my airbrush well. I take the entire airbrush apart and hit the parts with lacquer thinner (I use good, new, lacquer paint) then I coat the parts with Iwata Superlube. I even take the enclosed trigger spring off the bottom of the airbrush and spray it with lacquer thinner. Can anybody help me with this problem? Thank you.