Check the axle is straight by rolling it on a flat surface. If it’s bent it must be replaced.
If you need to replace the cones, measure the position of the one still on the axle, and make sure they go back in the same place so the axle is centred in the freewheel hub. The drive side may have more spacers between the lock-nut and cone. If you’re replacing the cones you may need different sized spacers if the new cones are shorter or longer than the old ones. It may be easier to replace the whole axle if you can’t find cones that match the thread on the old axle.
Repack With New Balls
Pack the races in the freewheel hub with new grease and press the same number of new balls – of exactly the same size – into the grease. Changing the balls prolongs the life of the other parts. If you’re not sure how many balls came out, or if you suspect that the freewheel hub was packed with the wrong number of balls, fill a race with balls and then take one out. The balls need room to roll around.