Cat 320BL Thumb and fuel shut off problem

My girl friend is having some problems with her 320 B on a ranch in Eastern Oregon. She can't really afford a service call and I'm looking into hopefully helping her. We don't have a service manual and I had planned on going to a Cat dealer for advice, and just found this site tonight. The Thumb circuit blows fuses when flipped. Have looked for shorted wires, but have found nothing obvious. I have no idea which spool is the thumb which is my first question. If I knew that, I could test the resistance and know if it was a bad solenoid or a bad wire from the switch. The second problem is that the key shut off stopped working and she has to manually pull a lever on the pump to shut down.( I have not had a chance to look at this problem) Would appreciate any advice or insight.

Thanks Jim

Cat 320BL Thumb and fuel shut off problem