Yes they do. The sensor closest to Ted mouth is used to detect a ball on the other side of the bulldozer blade. So if a ball were to end up behind it, the game would release the ball. It is also used to sense a ball strike to Ted's mouth if I remember correctly. Both sensors need to be adjusted correctly or you will have odd behavior. When a ball approaches the bulldozer blade, does it make the bulldozer striking sound? If it is working fine in test mode (operated by test buttons) but not in gameplay, then it is likely your sensors need to be adjusted. I have had mine just go out of adjustment before and it could just be due to component age, potentiometers getting touchy etc.