I haven't had the screw break off, but I am having trouble getting a good linear mixture. According to the instructions, you should tune the low speed screw according to how the engine throttles up through midrange. Mine goes very rich just above Idle and just below a hover speed. But Idle is Lean!?

I have the screw turned all the way clockwise that it will go and the idle is uncomfortably lean but when I throttle up to hover it goes slobbering rich and sometimes quits. Occasionally I can nurse it and the blade speed will pick up and I can hover comfortably and even FFF and loops. Then, occasionally it will go into that "fat" condition (usually after throttling back and back up after a loop) and I am in a panic descent with low rotor speed and no power cause it sounds very rich.

I am about to flatten this engine on the nearest railroad tracks and put a TT 50 in it.

I have been flying glow engines for over 40 years but this one has me baffled.

Any suggestions?