I too have an MDS .40 that came with my H9 Extra Easy trainer. Nothing but problems. Although sorry to hear you folks were having trouble too, I was glad to hear it wasn't just that I didn't know how to adjust it. (Rookie) I could never get it to transition smoothly. It would run fine from idle to just over half throttle, but I couldn't trust it to keep running at throttle positions higher than this. It would just stop. It also needed adjustment after EVERY flight. I have now replaced it with an O.S. .46 and love it. I also noticed on Horizon,s site, that the Extra Easy II they just released, (new paint job) now comes with the Evolution trainer motor. Not MDS. Probably too many complaints. I will say that the MDS was a very strong motor (lots of power) but alot of good that does you in the middle of a slow speed low altitude turn and the engine stalls. Been there[img]i/expressions/face-icon-small-sad.gif[/img]