There's one in the 3rd pic under the "fix for cupped surface" post.
You can see the top of a ball sitting on it near the lower right center edge of the pic.
If you have it at home, and you don't have a kid that might eat the balls, then there's no real reason to have it on.
Plus with it on, your gonna have to put the coin mech on as well, because the balls will be in the trap and the coin mech opperates the trap which drops the balls into the ready ramp....LOL..
But if your gonna put on location, then you might want to put it on.....elsewise you won't make no money! :-)