How do you fix a needle valve leak? my Os46 Fx has the same problem. Runs fine for 2-3 mins and then quits. Checked for all leaks,pinch test, foaming etc. I am suspecting it is a needle valve leak. The problem is that engine reaches peak rpm when the main needle valve is open only half turn from fully closed. It does all sorts of fluctuating and coughing and then quits. I'll never buy a Os engine again.