Replacing the switch membrane restored full function. Relatively easy. Had to pull stove out just a few inches to provide access to two side screws holding control enclosure. Then four screws on bottom edge just above oven door. Then a screw above each burner control. And one screw on the top edge at each corner (right screw additionally holding a ground wire). That allowed the structure to come out. Helper required to hold structure while I worked to unplug the old switch-membrane from circuit board and then peel it off front. Installed new switch-membrane by first plugging in its two cables, and then peeling adhesive backing off for adhering new switch-membrane to control surface.