Karyn

Hi Adam

In the bag of random screws, balls, etc., you should find some cross head screws that are long enough to go through the ball and the servo arm and have a nut (with threadlock) on the back.

Make sure you're using machine screws that take a nut and not self tappers. You want the ball on the reverse side of the servo arm to what would be called "normal", ie, closest to the heli frame, so that the link rods are vertical. Depending on the specific servos you're using you may need to file off the small shoulder on the ball to get clearance.

Karyn.