bgalles, first make sure the tail rotor and gear are pushed all the way on the shaft and the rubber grommet is pushed tight against the tail rotor. Then make sure the gear of the tail motor and the gear of the tail rotor a meshed together correctly. There are two screws that mount the tail motor, Loosen the two screws and put a peice of notebook paper between the two gear, slide the tail motor gear agianst the tail rotor gear and tighten the mount screws. Rotate the tail rotor until the paper is ejected from between the gears. This will give you the proper gear clearence.