while plowing snow this weekend my 1956 300 utility died while about 30 minutes into snow plowing. when it died, it seemed as if i was losing a bit of power then died. i then heard the sound of what could have been the starter motor engaged but surely some sort of a elec. motor sound running. last week the motor was popping a bit and backfiring out the muffler so before the storm i pulled the plugs and cleaned them and also pulled the distributor cap and saw the rotor had some crud on it so i cleaned it off.i thought i was fine because the backfiring was gone but it died anyway. does any of this make sense to any one. my tractor is the 4 cyl. gas model. thank you for any help.