I am spraying a shelf with lacquer......at about a 70%/30% lacquer thinner ratio. For some unknown reason, no spray comes out and I assume it is one of the 3 control buttons....but no turning of the buttons in either direction seems to help. Is the ratio to high? Plus, precisely what does each of the 3 buttons do to the spray? I have used the unit before...never toiuch any controls...worked perfectly...but suddenly...no spray but plenty of air emitted from the nozzle...no lacquer...only air????? Help? Pete Blaauboer....novice sprayer....(:-)