*HELP PLEASE* Rube Machine

Could anyone explain to me how I can get the cam targeter to work where the seesaw hits the tire? I'm trying to get it to switch from the metal ball to the planks then to the car and it just will not work now. I've tried Id/object fields, pressure sensors, lasers, buttons, along with various combinations of signal objects to try and figure it out but I'm not exactly advanced as I've been playing only two days and cannot figure this out for the life of me! Appreciate any help at all!