I have as everyone knows been trying to get my tractor starting by its key. I am aware that people on here think there is only one type of starter and flywheel . This is untrue. I have now done some research on this and found that there are four types of flywheel gears. There is one that is cast one that is aluminum and one that is plastic the last one of these was a ditch effort for Brigs and Stratton to save production costs and did not work. They abandoned this to go onto a further aluminum gear. There is also three types of gears for the starter and two different starters . Please check your model number and type to check you have the right matching components.