It's possible that the screw supporting the main ball on the top has come loose during transportation or use.
On the bottom of the unit you'll find a circle cut in the foam that allows you to access the screw that holds it all together. Be very careful at this point!
Turning the screw about 1/8th of a rotation clockwise will increase the tension in the unit. Note that if you do it too much the unit may seize up when spinning so only make fine adjustments and then test it.