Question about Deluxe Jazz

What are those circlular things near its rear tires? I cant seem to arrange them so that they will fit correctly. Also, the touch the ground so the car cant even roll correctly...
And ALSO! What is up with Jazz's head? Why wont it stay up?? Is there a way to suspend it up and make it stay up? Perhaps something to do with pulling his chest?
And ALSO! What is up with Jazz's head? Why wont it stay up?? Is there a way to suspend it up and make it stay up? Perhaps something to do with pulling his chest?