Greaves -
I've handled a couple dozen of these, and none of them are out of balance one bit, I'm thinking we have a user error here, unless you actually have a wobble? If you flick the tip with your fingers and it spins for a bit, there is nothing wrong with the bearings. Bearing tops don't correct themselves on the floor like fixed tips, because the tip is perfectly happy staying in one spot, the gyroscopic energy can't work itself out.