Ordered a set of plugs from Amazon. Decided to go with NGK as I've never had an issue....until now. Installed first plug after gapping and adding a dot of anti-seize. Threaded the plug down until it seated and then turned another quarter turn. When I removed the socket, half of the plug came out with it. Luckily, I was able to remove the threaded end of the plug. Posting pics, note the difference in the NGK plug and the Denso plug. Lesson learned but the NGK was the plug recommended in the manual. I have never had this happen in fifty years of wrenching.