I took an early non-comfortking Case 841 on trade a couple weeks back. Drove it onto a trailer and hauled it back to the farm, unloaded it and drove it 3 miles back to the house with no problem. Next morning I backed it out and it was running weird so I shut it off and when I tried to start it back up a few minutes later, it wouldn't even turn over. Long story short, the starter drive had gotten stuck out and it totally burnt up the starter. I had the starter rebuilt and the guy who did it suggested I go through my wiring thorougly because he suspected that since the battery was fully charged, it was likely a bad connection that caused the starter to stay engaged. So I've torn into it and have come across a component that my manual seems to identify as a circuit breaker. I can't find anywhere that I can get a replacement, and it is so corroded I can't imagine it has a good connection at all. Since this is linked directly to the starter solenoid, I'd like to replace it, but I'm not really certain what purpose it serves, so I'm not sure how to go about rigging up a modern equivalent. Does anyone know what I am referring to and what I can do to replace it?

Its a basic common part. Just go to a parts store that has some smarts (rules out oreilly and autozone) and ask for one. The starter likely died from its own fault of sticking engaged or a short to power on the s wire. Possibly the ignition switch stayed connected in the start position? Id bet on the starter having been sticky

I'd keep an eye on that starter switch staying in position, my uncle's 800 did that and he burnt up 2 or 3 starters forgetting to make sure it didnt stay in the start position before he got it fixed.

Yeah, Mopar has it right. I think it's a 40 Amp circuit breaker. NAPA has em. I can get you a picture of where it goes if you're lost. The wiring diagram in the service manual shows where it is located in the over-all scheme of the wiring. I'm feel your pain man, I labored over wiring (and particularly starter wiring) for a month or so 'til I finally got it right with the constant help, sketches, encouragement from this gang over here. I was stumped. I had it all wired wrong at first. I learned to never just yank all the wiring until I take pictures of what I have first. Those dinky little wiring diagrams leave a LOT to be desired. Don't be afraid to keep coming back...slim

You guys should see some of the diagrams i have to work with. Im a toyota master diagnostic technician by day. Those wiring books for each individual model for one years run might be over 300 pages anymore. 20-30 computers per car. Lin bean and can communication networks you name it. These tractors are a treat to wire on!

Just a word of advice, the breaker is in the generator charge circuit and a modern alternator conversion could possibly trip it from exceeding its rating with charge amps. When I did my 830 Diesel over I put a new heavy wiring circuit fom the alt output to the ammeter and from the ammeter to the battery post on the solenoid. I did not protect that wire nor did I remove the old. Most systems out there did not use a breaker in the circuit as Case did in those models.
If using a modern alternator as most are in place of the old low output generator and you want breaker protection, I would by 2--40 amp breakers and paralell them

Thanks for all the help! I stopped in at Advance Auto and the guy at the counter knew exactly what I was talking about and walked right over and grabbed one. Glad to have that resolved, I really just want to replace all the wiring and do it right, I don't know yet if this tractor will be one I hang on to for years, but if it is I don't want to revist an issue once I've already gone through it. Is the resistor something that I should replace as well or is that generally fine even in its 50yr old state? If so, is there another modern equivalent I can use for that?

I'm a mechanical engineer, and overall I hate dealing with electricity, but in my current job I do still have to design wiring diagrams for the aerial lift equipment we build, so this stuff isn't completely foreign to me, but as others have pointed out, the diagrams in the manual really leave a lot to be desired as far as clarity goes. The stuff I design for work is quite a bit more complex but it is a lot easier to follow and trouble shoot.

Go back to Advance Auto, they should have a new resistor as well.

What sort of ohm/amp rating would I need? Or should I just use something like this:

https://www.yesterdaystractors.com/S52671_Voltage-Reducer-with-Bracket_25302.htm

since as I understand the purpose of the resistor is to drop the voltage down to 6V.

Something like 5-6 v. Just to not burn up the ignition. I wouldnt think there would be a need to replace the resistor unless it got badly corroded or appeared damaged. Hope i didnt offend you in some way. Didnt know your level of experience and background.

I gotta be careful. Seems everytime i answer someone on here their problem then happens to me. My resistor failed just now. Just like shut the key off. Man...