So was riding chappell creek yesterday with deep powdery snow, ran flawless and like a top all day long. Put it in the trailer cranked the heat and half dried it up so skids were clear. Went to Allen today and again was running stellar flying up the trail to the 6km mark. It then felt as if it was not running as smooth, I could feel it through the throttle if that makes sense. So I pulled over, was idling ok but decided to turn it off. Went to start it 5 mins later and could not get it too fire, engine still turning over however via both the pull cord and primary clutch. Pulled plugs and they went dark (black) and dry as could be. I put new plugs back in but would still not go. I tested each side for compression with one plug off at a time and pulling the chord and each are puffing what I believe to be normal. Anyways towed it down and now I am trying to find a solution now. Thinking its either a frozen fuel line that froze on the way up the trail and choked off fuel. Or a fuel pump or filter. Hoping this isn't signs of piston slapping and wear against the skirts already. Sled has on 450 miles on it now. Any advice and thoughts are appreciated!