That was a lovely find. So glad your brother was alert to the situation. I have one in the exact same treadle base with lotus decals, also with the back clamp presser bar, and the number was allotted in 1922. I didn't pay a fortune for it, but it's not in as pristine condition as yours, and the cabinet, which was beautifully refinished not too many years before I got it, has a water ring from a plant.