I think you’d be able to determine the start date for Panasonic Jet-Flo uprights from the date Hoover sold their Dial-a-Matic patent to it’s parent company Matsushita of Japan. If I remember correctly, this was in the mid-1970’s. By that time, the Japanese company had already started selling uprights and canisters in North America - though in very limited numbers. But the purchase of the DAM patent really launched their successful position in North America’s floor care market.