Here's some picture's to look at:
The upper arm gets raised to knock the ball off of the rack. It is then lowered. The scooper arm scoops up the ball and holds it against the upper arm. When the upper arm is raised, it is able to fling the ball over the rack every time.
To see the video look here:
http://www.youtube.com/watch?v=eeVu1LEiB30
Let us know what you think.
Raffi