If your going to replace ALL the bearings, the easiest way is to put the case halves in the oven just below melting point of aluminum, and they will just fall out. Have the replacements packed with grease in baggies in the fridge not freezer, and ready to drop in before halves cool too much and the case halves will cool and shrink around the bearings locking in place. I've seen people mar bearings and the hole they go in numerous times, to where the case half was ruined, and case halves are not cheap.
Clean the cases.
Preheat the oven to 275F.
Place a biscuit tin on the lower shelf.
Place 1 case on the shelf above, bearing side down. Bake for 15-20 minutes.
The aluminium will absorb the heat faster than the bearings and the bearing will drop out onto the lower shelf.
If there are still bearings in the case, remove it from the oven and smack it down onto a wooden board and any remaining bearings will fall out.
I've used this method multiple times now on multiple platforms and have not ran into any problems at all. But your right the melting point of aluminum is over 1000 degrees, I dont have an oven capable of getting that hot, but luckily 275-300 f is plenty hot for bearing removal.