I have and having a problem with my new R40. It will be running and I will be playing with the steering and it will just turn left and kinda stick there for a few seconds. Then it will be back to normal unitl it does it again. I have a Hitec digital servo.
the r40 is mostly carbon fiber. make sure your antenna wire and servo wires don't have a nic in them. also that your receiver is not touching the carbon fiber. if it is put a little piece of foam under it.