I think (especially considering the different needs for 6:28 PM and noon) that you'd need some orthogonal magnets set up - have one set of strong magnets around

I think (especially considering the different needs for 6:28 PM and noon) that you'd need some orthogonal magnets set up - have one set of strong magnets around the center of the hub to keep it in place while providing a minimal amount of field interference to the magnets driving the hands. I'm not an engineer but I think any solution that starts with trying to suspend a clock using magnetic forces applied to the clock hands is going to be incredibly complex and hour-minute cross-overs would be extremely delicate maneuvers considering how much of a raw magnetic field you'd need to be projecting just to keep the clock face floating in air.