The key swich is new
The key swich is new
The reason it just sputters,and won't shut off,if I'm correct,is that the key switch isn't grounded,properly.
Try this test:
Take a piece of wire,about 2ft long,and strip both ends about 1 inch.
Start the tractor,and when you shut off the key,touch one end of the wire to the switch body,and the other end to the engine mount bolt.
If it kills the engine,then the switch needs a better ground.