The whole key is to GO SLOW. 1/8 turn to barely unseat the plug, carb cleaner to the bottom of the hex of the spark plug...you'll see air bubbles as it goes down the threads. After 15 minutes, I went back to the plug I started with and retightened back and the 1/8 turn loose again. Repeat. And then a 1/4 turn out then tight. repeat. You get the idea. Before the plug comes all the way out, take an air hose with a rag and blow out the excess carb cleaner. I had all eight come out, not one broke. And yes, they do screech a little when coming out.