Are you sure the tail motor isn't burnt out. As soon as I installed the gyro and the ESC, my original tail motor burnt out. I replaced it with a GWS motor and have not had any problems since. You could also check to see if you have voltage at the motor using a voltmeter. I don't have mine here right now to tell you what it should be for sure, but you should have some kind of voltage at least over 3 volts.