Tractor Repair: Ford 5000 Diesel starter troubleshooting and replacement, ford 5000, gauge wire

Question
I have a Ford 5000 Diesel and the starter seems to be shot. I have checked the batteries and all the wiring. No luck. Any suggestions?

Answer
check the solenoid, check the engizer wire (it is the one small gauge wire out of the two heavy gauge cables) when the key is turned to the start position (or the starter button depressed with the key on) you should have full voltage (6, 12 or 24 volts depending on the cranking system) if not this needs to be repaired, if it is getting power but voltage is not going from one cable to the other, and you hear no clicking sound replace the solenoid.