The ring rotates and sometimes feels like there is no compression when they are in different spots?? That's what I found in a couple of mine anyway. I don't use the locktite and don't have anything come loose. I run up my engines until they are hot and then tighten the muffler lock nut again. A valve adjustment would be the first thing I would look at if the engine is running hot. If it is still doing it then I would send it right back to the service center, like beach said, Horizon is very good about doing repairs or replacement, for the price of the engine there shouldn't be any problems at all.