What I was wondering about is him useing a ball link on the control surface end? Unless a metal or heavy duty control horn is used putting a ball link on that end is a bad idea. Even then it is not the best idea. A clevis can push and pull in line with the horn. A ball link will try and twist the horn with every deflection. On a standard plastic control horn the deflection is a lot. It is doomed to fail and cost you the plane. The ball link should be on the servo end with a heavy duty arm. Then a metal clevis on the horn end.

Just my.02 David