Cub Cadet 107 not charging - I am stumped

Hi everyone, it has been a good while since I've been around here. Been busy with other hobbies and other projects, but I have been working with and on my Cubs and the bigger IH stuff as well. But right now I have hit a road block that has left me completely stumped, and I would like some advice.

Today, I have been working on my 107. Trying to figure out why it does not charge the battery. Last fall I had it at a show, and loading up to go home could not get it started because the battery was dead. I jump started it when it was home and determined it was not charging. Ever since then I have had to jump it to get it going again. Today, I put a good battery in it (seemed like the other one had gone bad) and I got it to start up on its own, but only one time. It drained the good battery down to around 9 volts pretty fast, and I once again had to jump it.

I messed with the adjustments on the voltage regulator for quite a while. For a bit it would seem like I got it working right, but it never actually was. Battery would drop back down to 9 volts not long after jump starting. After giving up on the existing regulator I tried two others - one that was a mystery and one that was known to work, as it came from my long term project of a 147 and was charging when I had that running. All 3 regulators wired up the exact same way and all the wiring is correct. I did not try and adjust these two regulators. None of them provided any difference and it still will not charge. I am now completely stumped as to what the actual issue is. Do I need a new regulator? Is there something wrong with my starter-generator? I know everything used to work.

The shows around here are fast approaching, and I would like to get the 107 maybe out to the county fair next month, or if not there the Alexander steam show in September. I am disappointed I have left it sitting around because this issue has prevented me being able to hop on it and go. Thanks in advance and I'm hoping to get this figured out soon.

While the tractor is running, temporarily ground the "F" terminal on the starter/generator. This will cause full output if it is working properly, peg the ammeter to the 'charge' side, and you should read 15+V across the battery terminals. If not, the field coils on the starter/generator are faulty. If that did cause it to charge, you have a wiring or regulator fault. Since you've tried 3 regulators, that isn't likely the issue.

These tractors had wiring with cloth insulation that does not age well. It was bad 15ish years ago when I last had a tractor with that kind of wiring. I can only image how deteriorated those are these days. If I were you and were planning to keep the tractor, I'd replace the wiring harness, as it is very likely to be full of broken, exposed, and corroded wires at this point.

The wiring harness is already a replacement harness, although not new. Came from a tractor of the previous generation. The original one was completely destroyed. I will try that test out and see what I find.

I'm not sure that harness was original to the tractor it came from anyway come to think of it, the wires all have plastic insulation and not cloth. If it comes down to it I'll probably just buy a whole new harness. But not going to do anything yet until I test my generator.

Took some pictures last night while I had it out, might as well post em.