Here's why any rotating perpetuum mobile device cannot work regardless of the principle (gravity, magnets, springs, balls, ...). Anything that moves on it's own is moving because it is lowering it's potential energy. You start at 12 o'clock, and it moves to 3 o'clock because there, it will have lower potential energy. Then it continue to move but eventually it will reach the starting point (because it is circular). But you already know that potential energy there is higher, so the device will not move there because it wants to lower it's potential energy, not raise it.

So any device that at some point reaches it's starting configuration cannot work because the potential energy is the same. If you put ball on flat plane it will not move sideways because potential energy is the same there.