HI Auna, I think I may be the one who posted about the Youngstown disposer - my folks did replace one that was in the sink of the 1957-ish house we moved into in 1970. The disposer was really, really worn out and we were following the advice of neighbours who had replaced the same unit.
As for the cutter blades, I think they'd still have been something like the 'teeth' that surround the grinding chamber of most disposers. They would not have been sharp, like a knife or meat grinder cutter, but they must have had some kind of edge that would strike the food waste and would wear down over time. Ironic that Youngstown came up with this concept to 'double the life' of the blades - their very early disposers from the 1950s had a reversable motor which allowed the operator to grind in one direction one day, then the other direction the next day. Closest I had seen to that was the auto-reversing ISE/Kenmores back in the 80s (I had one of those in the very first house I bought!).