Stop & think
Why are those witches there ?
The seat switch is there to prevent you doing stupid things like getting off with the blades running and shoving you hand into the discharge chute to clear a blockage plus to prevent it running away driverless should you fall off
However the engine has to be able to run when you get off to move things or open a gate .
SO the seat switch works in combination with both the blade switch & the parking brake switch .
On top of this some of the switches are open then close when the plunger is down or visa versa so it is easy to get the wrong switch .