What I am finding with the servo horn is that the ball stud is backing out. The rear motor guard hangs down a slight bit below the xhassis and can catch the ground. I just shaved a little bit off with an exacto and haven't had a problem.
There are only a couple in the country right now so there won't be much feed back until they start to get out there but I will get a set up and some pics up rhis weekend.