-
Yes, I did this with the hub bearings, worked a treat. The freehub one is shot though. I have no idea if you can get it out because even the diagram doesn't show it as separate from the freehub?
I believe the rear hub bearings are: https://simplybearings.co.uk/shop/p6183/SKF-60012RSH-Rubber-Sealed-Deep-Groove-Ball-Bearing-12x28x8mm/product_info.html
Not sure if the freehub one is a different size however.
can you measure the bearings? If so they might be replaceable but you'd need to be able to get them out and new ones "pressed" in.
I've had some success in the past taking the seal off sealed bearings and cleaning in white spirit and then repacking with fresh grease obviously if they're rusty they'll never be great.