FORD 7600 Electrical issues

I was encouraged to repost this as a new thread, for reasons I do not entirely understand about classic and modern views of the forum.

Last winter got a 7600 1978 no cab. Love the turbo. reminds me of the sound my 1966 corvette 327cc 350hp made when sucking air through the four barrel Holley. Wish I still had that car.. Apparently the tractor was parked outside for a while before it came here sheet metal rusted, instrument panel water damaged, but started and ran fine to get chisel plowing done last spring.
Alternator replaced when the light came on. Starter quit, all corroded inside, replaced, but not even a click of the solenoid on the new one. Lights on the instrument panel occasionally worked. Saw smoke come up from under the sheet metal over the tank once while trying to start, figured I toasted some wiring. Ordered new wiring with connectors from Agri-Sevices (excellent product and service). New battery, cleaned all connections. Replaced voltage regulator. New key switch. New instrument panel. Got instrument panel lights now but one click of the starter solenoid and then nothing and lose the instrument panel lights. Meter shows 12.4 V to starter solenoid and key switch. Meter on neutral safety switch wires shows resistance in Hi and Lo, and zero in neutral, so I am assuming this is working(?). Since it was in the shop for all this, repainted the sheet metal, has good rubber on all four. I have been thinking the tractor is worth all this investment for my long term use, but I am really baffled by the electronic problem.

Previous post replies suggested moving the starter ground to a mounting bolt (done; no change)
Trying a remote starter switch on the starter solenoid to isolate wiring vs starter (done with a screw driver; no reaction)
After trying to start with the switch, I'd lose power to the instrument panel- blew the breaker I'm guessing so there maybe a short somewhere.
Even though the meter showed the neutral safety switch seems to be working, I bypassed it with a wire loop. Turn the crank and off goes the starter (YES), but then would not stop when I turned the key off (DAMN)

so here's where I am:
it appears I have a short in the neutral safety switch or wires under the shifter plate?
But why did the key switch not stop the starter from cranking?

any ideas very welcomed.

This probably isn't the turn screw A and replace dodad B but will give you a couple of possabilities. It's possible the magnetic switch in solenoid was damage during earlier shorts and high amps. When starter refuse's to stop when key is turned off,remove wire from solenoid that come's from key switch. If starter continues running,replace solenoid. If it stops when wire is removed,wire is connected to something else between key switch and solenoid,,,,OR,,,,key switch is defective. To test key switch,disconnect wire at solenoid then connect it to a test light. Work switch to see if light react's as it should. Hope that narrow's it down.

Thanks da.bees

I do have a Large Ford Shop repair manual that cover the 7600 tractor. It is For Sale at a reasonable price. PM me

thanks nashranch, I have that shop manual already.

Fixed! Loose wires on the neutral safety switch.
All systems go!