Hello guys, after reading for long time about the rudder coupling, I will strongly suggest that before cutting or making any kind of mods it is better to check if the model surfaces are straight, my UCANDO flew fine from the beginning without rudder coupling or some times just a little but was due to the high wind, so even if it is an ARF it has to be right!, so measure distances and angles, this is based on may experience with mine.
Good luck and happy flying