Hopefully I can get some good guidance here on this issue. 30 seconds into the flight I fly my 130x out about 100 - 150' bank it to the right to come back at me. Halfway thru the turn while the heli is sideways in reference to my vantage point, it, without any additional stick does a quick 1/4 turn as if it hit a missing tooth on the gear. I replaced both c&d gears with stock plastic gears, then one metal and one plastic.. still doing same. During this split second loss of directional control of the rudder I spend 15 seconds trying to control the heli from a crash and burn. I am getting ready to take the tail servo off and clean it. Any input?