solenoid is new, but tractor still won't start. I took apart the key switch and found a lot of grease and dirt where it should not be, clean up and now the lights work and the clutch for the lawn mower works but the key still won't engage the starter. I no the starter is good, because I took it off and check it, it works fine. when I turn the key on and jump the solenoid the tractor starts fine. What is the problem?