Wheel Bearings coming loose

If your pulling it apart, I would make sure there are no areas on spindles that have been nicked or gouged. This could cause areas of high metal that won't allow the cone to slide over like it should. As 273 stated earlier slide the cone (bearing) onto the spindle without the hub on, this will tell you if they are free to move like they should. Also I'd check the races to be sure they are fully seated in the hub, if they're not they could be "walking" with the load on the bearing. As already mentioned make sure the outer races are not turning in the hub, I had this on a Charger and it would cause a vibration.