Purchased burner bowls and burner bowl seals for replacement. This was more difficult than it should have been. My GE stovetop sold as a Sears Kenmore included a parts list and exploded assembly diagram, but while my stovetop had one size of black burner bowl, the diagram and list included three sizes, and the part numbers listed turned out to be for white bowls. A search for "burner bowls" gave me three black bowls not listed but adjacent part numbers, so I assumed one of those must be the right one. Their diameters were never mentioned, but the shipping box sizes were listed, so I ordered the model that most closely matched the shipping box size, and ended up getting the right bowls after all.
Installation was as simple as removing the two screws holding them in place, removing the bowls, old seal pieces, and rust mess, then installing the seals around the bowls. The burner bowls then readily installed with the two screws each.