If its ball bearings, you can likely get new ones easy enough. Most bearings are an industry standard type, and you can cross the number to get one from anyone. If its a bronze sleeve bearing, those can require some other work. If its not too bad, you might just be able to soak fresh oil into the felt after cleaning the inside of the bearing and shaft off. If its really cooked on, I've had some success in heating the old bearings to cook out old oil, then submerging them in fresh oil and applying vacuum to re-impregnate them. Usually around a 10 weight oil works pretty nicely for this. I've used engine oil as well, and it also works out OK.
Surprised they can't fit some sort of universal replacement type fan motor. This isn't rocket surgery, its just a simple electric motor that needs a shaft of the right size and shape and appropriate mounting hardware. Unless your central AC stuff down there is grossly different than ours here, it should just run off mains power and probably it mounts using a couple of studs sticking out of the back into a bracket.