RE: spark plug falling out of zdz 80???????????
Hello!
Huh? What about the set screw or the new ones that use two set screws on the holder? Use some blue loctite to be sure they don't back out while the engine is running. I talk from experience! Push the plug firmly down on the sparkplug and then tighten the set screws. No need for anything else. Of course, if you're missing the holder, then that's a different story. You need that part!
Good luck!