My MTD 115/76 with a Tecumseh Formula 12.5HP Engine was working ok but then will no longer start. I have changed the inline fuel filter & fuel ssems to be getting to the carburettor ok, but there is no sign of wetting on the spark plug. Reading comments there seems to be an issue with this type of carburettor involving a solenoid. I cannot seem to find any specific information on these carburettors. Should I look to replace it or is there a better alternative to fit? Any help would be much appreciated. Terry