Oh wow, can't say it doesnt look like every other brands' hand vacs of the time.
Let me make a guess here;
E BG HC 29104
electric, blue grass, hand cleaner ? 104th day of 1929 (April 14, 1929)?
Belknap Hardware was one of the largest hardware companies in rural America in the early 1900s. The company's headquarters was in Louisville. They sold several lines of tools and home products under brand names John Primble, Pine Knot, and Blue Grass.
If anyone can look for these "Want books" / catalogs from 1929 and up, it likely might be in them somewhere.
What you found is a hardware store's private label hand vacuum, that's pretty rare, especially with original bag! Likely was sold to farmers to hoover out their town cars before church and market day, that's the only time a man would be vacuuming in those days! lol