You've had the hub apart? You changed the balls out? If you don't mind taking it back apart (no big deal) you can take the cone you removed from the axle and see if it seats into the bearings correctly or not. if the bearing hits the center of the cone race with the bearings in the hub, they are most likely correct. if the cone doesn't drop in and the bearings just ride the edge of the cone, you need a smaller bearing size.