the engines have a 1 year warrenty, give them a call, can't hurt right ? As the engine heats up it expands thus loosing compression and power. I found that I needed to turn in the needle valve a few clicks every minute or so to keep it flying, soon it would not lift, I tryed every thing I have read here plus what litemachines told me to try but it boild down to bad motor. Call them they can walk you thru a diagnostics. Good luck Alan