Hey, just a quick thought on your yaw problem, you said you lubed up the inner and outer shafts, Make sure the gear on the bottom connected to the inner shaft has the screw properly fitted into the notch at the bottom of the innter shaft. If you lubed it all up, which really is not necessary unless your having some issues, that gear could be slipping. A small slip could allow the heli to fly but stop the top rotor from turning at the proper speed, causing yaw issues. Just a thought.