I don't remember about that but offhand I'd say you only need to remove the unit from the case. If you want to know what is north and south, just hold a compass near it. If the needle runs toward the area...you're looking at the south pole there. If it runs away...you're looking at the north pole in that area. Opposites attract. Same with the magnets you have. You can use the compass to mark those as to N or S.
