This part is the replacement grommet for your cooktop or range. It is made of black plastic and is approximately 1 ¼ inches in diameter. This part may also be known as the cooktop burner knob gasket, ...
I had used a pan too large for the middle burner - result: melted knob. Just pulled the old one off (up and straight) and then pushed the new one down firmly. Make sure the indicator line is pointing at you, so the flat side of the spindle matched the flat side of the hole on the knob. Easy peasy.
First I drilled out the screws on the burner as they were fused. I opened the stove top cover to access the underside of the burner. Removed the orifice holder, by disconnecting the gas line with a line Wrench and the electric cord.
The trick is to be careful with the gas line. Also when you go to replace the orifice holder you will notice that the holes are not threaded. The metal is soft and you're supposed to just screw the screws into the holes and let them bite into the metal. Then you reattach the gas on the electric and put the stove top back together.
