I have a riding lawn mower, model 917.258140. The ignition switch won't engage the starter motor. If I manually jump the solenoid terminals, the starter engages. Does that mean that my solenoid is good or could it still be faulty?? Maybe I have problems with the ignition switch, but I don't suspect that.... Can anyone help with this? I don't know how to check the ignition switch or the solenoid to verify they are good or bad and don't want to just start replacing parts...