Yesterday my 60 started right up and ran like a top when warming it up to plow snow, pulled it 200' out of the shed and it shut down like someone turned off the switch and will not fire (white smoke out exhaust). This is the second time this is happened this winter and it's been a cold one here in MN. After the first time I waited until warmer weather and changed points, condenser, rotor, fuel filter. Tractor started but ran rough, moved the carb needles back and forth a little and it smoothed right out and ran great until yesterday. I use non-oxegenated gas because of better shelf life, my tractors don't get used that often and this one sat for years before I got it. Using this gas could I have water/fuel issues freezing up the carb or any other suggestion would be a helpfull.