Morning Johnny 007, The first thing that came to mind is: Are your tail rotor blades trim? They should be in a vertical position. And have equal throw in each direction while moving the collective stick side to side. If not this can be adjusted easy by your sub trim in your transmitter, a little goes a long way
. Also look at your tail servo arm to the push rod, is it 90 degrees? Another visual check of your tail rotor blades, watch them automatically move as you push the helicopter nose in the opposite direction. You'll notice that the front of the blade (leading edge) also change. Hope this helps friend