Hey, I have a raptorr and mine used to due this. When no throttle is added are your tail rotor blades perfectly straight and no pitch on them if not, move the servo around and stuff. If they are perfectly straight then move the servo to where that there is a little pitch on the blades to counter react the left spin. Also have you taken the servo horn off of the servo because the tail slide shouldnt move all the way over so take the sero horn off again and put all the controls at center and put the servo horn back on so the blades are perfect. hope this helps