Need some assistance. Replaced the 10 in my 100 with a 301. Is a new one, ran 30 minutes 4 years ago. Been covered since. Good gas flow to carb. (Walboro) Stated, ran couple minutes the died. Have cleansed the points. Trash in carb? Short of totally removing the carb to clean, anything I forgot? (I hate removing these D things!) Also, is there an "O" ring on the gas line where attachs to carb under the connection nut?