I have a b7800 hst 4wd that is not cranking. no engagement from the starter from the key but you can jump the starter

Hi, My name is***** will be glad to try to help. We can follow up as needed on here. Professionals are not employees of the site but users of the site and help on here as time allows depending on their daily schedule.Sorry to hear you're having these troubles with this tractor. Unfortunately, a visual inspection is very inaccurate when it comes to electrical troubleshooting unless you see some obvious damage visually. Using a voltage tester,Verify battery voltage in and out of the ignition switch switched position. Test for power at the starter solenoid signal wire or S terminal with the ignition switch in the cranking position. If you have 12 V there or battery voltage but no response from the starter solenoid when attempting to crank the engine over, it's an indication that the starter solenoid itself has failed and is why you can jump across the solenoid but cannot get a response from the ignition switch. If there is no battery voltage at that signal wire with the switch in the cranking position, then you have a problem within the ignition circuit or one of your safety switches and wiring. Be sure to check your seat switch and clutch/brake switch. Also check your neutral safety switch as well for proper operation. Inspect the wiring and connector pins or any corrosion or damage that would cause a short or open circuit. I hope you find this information helpful. Reply back with the results of these checks if any further help is needed. It is a pleasure to help anyway I can.