Guys, the PC is a random orbital, which means it is designed to orbit without spinning. It does this whenever the pad is touching something. The reason it spins when the pad is in the air is because the counterweight which makes it do the RO action is causing the center of gravity to shift, which makes it spin. Kind of like how a hoola works. Do a search the the PC and you will see that many have discussed this and even demonstrated this to themselves.