if you kept moving parts oiled, the odds are that rust is only on the surface, and hardly matters. Clean it off, and use something to prevent future rust. If the rust has affected moving parts and it's now stiff, try oiling it and see if you can you can work things totally free.
If not, try a penetrating oil designed to free frozen or rusty bolts, like "Kroil" or "Liquid Wrench" These have chemicals in them to break up rust and loosen frozen or binding parts. Be sure to wash these out afterward, and reoil.
As to it's former glory - cosmetically probably not, but mechanically no problem unless the rust damage was pretty sever.
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