about 3 days ago my little bro was out on his 580, and ended up phonin me. said he thought the sled might be blown, so i went out on the zrt and sure enough it was blown. so i towed him home and me and the old man popped the head off. the top ring on the piston snagged the exaust port, and broke a hefty chunk off the top of the pistion, which scored the jug and musta blew out the exhaust, because no further damage, that weve seen yet has been done. any ideas why the ring woulda snagged???