No big deal, spend a few dollars on a Korky replacement and be done with it.
I did and I have been as happy as Larry ever since.
It's not worth getting into a flap over a flapper Dunbar Plumbing.
There are other problems with this flapper too. On the early versions of the Cadet 3 it would stick open if the chain was very slightly out of adjustment. Again the Korky seems to fix this.
But I continue to stand behind this Great American Product.
God Bless America and all named after Her.