I have changed starter,solenoid,and key switch.I can short the solenoid and it fires right up,mows all day,when I try to start it with the key,nothing,no clicking from the solenoid tho there is one audible click from the rear of the engine.The mower did start fine with the key,then it got to be a random problem now it will not start with the key switch ever.Please help am at my wits end with this.