It for sure wasn’t broken on assembly, once installed, I watched it for several ups/dns thru the exhaust port before installing the muffler. It broke right in the center of the exhaust port. I think I would have seen it. I will measure ring end gap on the next one, and look for the spec, before final assembly. I’ve taken a stone to the damage on the exhaust port, both top and bottom. I finished with 1000 grit and checked for bulges at the spot as well using a bright light and a straight edge. It is flat, what’s left is a small divot in the center of both the top and bottom walls of the exhaust port that probably will leak something, maybe not. I’ll have to try it to see . Waiting for parts.