[Jay O'Donnell]

We had this same problem with out prototype last week. I would suggest a number of things to check...
1) check whatever you are using to attach the wheel to the motor.
2) do what was already said in the video above
3) balance the weight of whatever is on the wheel to allow you to pump it up with a small piece of aluminum
4) make sure your shaft and bearings are straight (assuming that is your system)

Hopefully this helps, good luck!