tom wrote:
I have a toilet that has a rigid plastic rocker as the flapper, with
pegs, not holes on the flapper.

This is an old flapper. I wonder where I can find one that will work.

Call the manufacturer. You can usually google up a phone number. I
just went through the same thing with a newer toilet where a trip to
Home Depot came up with clerk selling me the wrong flapper.
Manufacturer gave me part number and told me Lowes, but not HD, sells
them, which they had in stock when I went there. Manufacturer also gave
me two suppliers phone numbers where I could have ordered by mail if needed.

Frank