Since no one from Hobby Services most likely will answer your question until Monday I wonder if you have already removed the prop adapter to make sure it is seated properly on the rotor it is mounted to, and make sure there is no dirt or anything under there... Hopefully the engine was not in a crash and the crank or hub is bent...Hobby Services is very good on warranty problems so I would not hesitate to give them a call... They were very helpful with a problem I had with my 43EI... Good Luck! Larry