ORIGINAL: clarencem
check and clean and relube your one way bearing. you may even need to replace it. i am assuming that this is set up like my t-rex 450. It will start to do this when the bearing is starting to go bad.
you maybe right, thay he need a new set of bearing.
RickP, have you also ground your tail; main bearing (shaft) to your motor mount, is your heli belt drive or torque tube type. I grounded mine to reduse the interference.