Wobbly ball falls down here, and comes back up?

Santa brought me this clever device which I love. You put these wobbly ball things in the top, the roll down the slide and then click back up the steps on the other side before going back down. Very noisy as well! It appears to be some sort of primitive perpetual motion machine, but I'll keep quiet about it for now. Don't want to be accused of breaking the laws of thermodynamics.