I'm having a similar problem. With a lot of force I managed to get the old plug out, and when putting the new plug in, the directions say to fit it until it bottoms out, and I'm not sure it is bottoming out. I do hear little clicks as it gets close though, how do I know what gas setting the plug is on, or if it's seated properly? With the old plug, one number would be face up, and that was what setting it was on.