Crystal.  Many of the vacuum parts makers and suppliers stocked up on genuine HOOVER parts and made to fit in anticipation of the transition to TTI.  Probably making the parts scarce now and taking longer to get.
 
For all the big box store buyers, here's where a business relationship with the local vacuum indy comes in handy.  Why? Availability of parts after the fact, like a buyout and discontinuation.  
 
Many of the old timers in this business remember when HOOVER made large belts for its old style metal uprights and smaller ones for the 60 models and above (like the Convertibles).
 
HOOVER discontinued the larger belt in the 60's and was soon followed by the vacuum parts makers too (like Essco) forcing users who still had the old style metal HOOVER's to use the smaller newer belts.  Not really bad, but the old vacuum bearings couldn't take the tighter belts for long.  Some indys resorted to "used" stretch belts to keep their customers (usually seniors) with the right belts.
 
Anticipating this, I bought a boat load of the belts.  I think I paid a nickel a piece.  Just for my old customers.  Low and behold, when I moved in August 2006, guess what I found buried away and in storage since I sold my business in 1992.  A bag of of old large Essco belts for the old style HOOVER's.  Still in good shape and usable.  Gifted them away.  A piece of vacuum parts' history.
 
Carmine D.