Matlab Animation of motor

I am trying to recreate this engine in Matlab: http://www.animatedengines.com/co2.html. I am looking to use handle graphics in order to animate all of the moving parts. I have all of the stationary parts already programmed. Right now I am working on getting the ball to move up and down, but I cannot figure out how it works. I don't have a very clear understanding of how handles work and what I need to do to get the ball to move. Any insight would be greatly appreciated.