Bumpers And Bags
Charles, I really don't know if the center rivet was factory or added, but I think your theory is a good one that Hoover may have noticed the droop and corrected it during the run. I also noticed that the bags on yours and mine are identical, but John's is slightly different--ours both say "it beats as it sweeps as it cleans" and his doesn't, and the typeface used for "The Hoover" is Gothic on ours but an oldstyle face like Caslon or Goudy on his.
Either way, all three of them were either made in 1935 or 1936. The serial # on mine is 4851141 if either or both of you want to compare numbers to see which is older or newer. Who knows, depending on how close the numbers are, they could have been made the same year, month, week, or maybe even the same day! Would be interesting to find out, wouldn't it!
Jeff