How do you beat the final boss on "DUM DUM and the Iron Golem"?

One of the stakes where the golem enters is loose, pull it out and attach it to the cart on top of the right tower. The left tower has a rope, connect it to the cart. I got stuck at this point. In front of the cart wheel is a small wedge. Click on it to get rid of it. When the golem lowers his hamer, the cart with the spike will be pulled forward, killing him.