As one of the Hackaday comments mentioned, the original Walkman must have used samarium cobalt magnets rather than neodymium magnets. SmCo magnets were known si

As one of the Hackaday comments mentioned, the original Walkman must have used samarium cobalt magnets rather than neodymium magnets. SmCo magnets were known since the early 1960s but neodymium magnets were discovered in 1984, 5 years after the Walkman launched: https://en.wikipedia.org/wiki/Samarium%E2%80%93cobalt_magnet https://en.wikipedia.org/wiki/Samarium%E2%80%93cobalt_magnet https://en.wikipedia.org/wiki/Neodymium_magnet#History https://en.wikipedia.org/wiki/Neodymium_magnet#History