[jacquesm]

Amazing mechanics, there is a lot to learn by just examining the mechanism of these. As a kid I had access to one, my mom had one at home. I distinctly remember how fast the ball moved because I got a nice 'J' imprint on my pinkie trying to see what would happen. That hurt (predictable). That taught me not to mess with live machinery and to have respect for things that move faster than you can follow with your eyes.