The axle is machined with a step that is larger than the rest of the axle and fits the 12mm i.d. of the bearing snug but not tight. With the locknuts removed, you should be able to tap the axle out one side through both bearings. Generally the bearing's outer diameter is an interference fit into the hub. Since aluminum expands more than steel when heated, you should be able to heat the hub to about 200F with a hair dryer or heat gun, then bump the bearing out with an extractor or a punch from the opposite side. Be careful not to apply too much heat to the spokes if using a torch or heat gun. If they turn blue, they may be toast.
__________________
My C&V Bikes:
1972 Bottecchia Professional, 1972 Legnano Olympiade Record,
1982 Colnago Super, 1987 Bottecchia Team C-Record,
1988 Pinarello Montello, 1990 Masi Nuova Strada Super Record,
1995 Bianchi Campione d'Italia, 1995 DeBernardi Thron