I have a Craftsman 917.272021 16.5 hp lawn tractor that suddendly will not start. I have replaced the battery and solenoid but when I turn the key I sometimes hear a click and other times nothing. The fuse is ok. I've made sure that it's in neutral and the blades off before starting. I have placed a jumper on the starter and + battery terminal with the key on and the motor will turn. Could this be a safety switch problem? I'm aware of the one under the seat. As I look at the scheatic and electrical diagram I see other switches but I still have a hard time finding some of them on the tractor. Is there a switch for the brake/clutch? I do have a multimeter but I'm not sure how to use it to test the switches. Yes, I'm a newbie at this kind of repair and would appreciate your help. Thanks!