<-------- OP is not a "dude".
I've owned my tractor, Jane Deere, since 2011, second owner. I have maintained & mowed multiple pieces of acreage since. Cleared my most recent property (the flat pasture that busted the bolt) using it to mow down 10 years of over grown brush (with OLD rotary cutter) and move limbs and trunks from 64 trees I cut down, dumping them in construction roll offs. I mainly used Jane for putting hay rolls out and mowing pasture. On a few occasions Jane has also moved a fair amount of dirt and pulled out vehicles that get stuck when the ground becomes a sponge. While I don't necessarily understand every thing I know about tractors and accessories... I assure you I am very thoughtful about how I operate her to minimize the necessity of having to go to the only local shop who works on these size tractors. There is no glut of shops in my area. I'd go to the Kubota dealer but they don't want to touch JD. MY boyfriend is a City Boy, so no help there. So I try to employ work smart not hard.
Ya'll may not have had the pleasure of being treated like a dummy who couldn't possibly understand "machines" or someone who's bill can be padded with extra stuff because it won't be obvious that fluff has been added. I have and it never makes me a favorite customer. That's why I joined this forum so that I could hopefully get advice to help myself where possible. My mower is new. I incorrectly assumed that it should function as intended and not have a failure so soon. Because it's new, I don't want to do anything that would void any warranty, if there is one. In the industry I work in I see many situations where a consumer attempt to remedy a situation is a perfect excuse for the contractor/manufacturer to automatically claim a warranty void - even if the consumer's attempt was benign.
The original mow deck that came with Jane (2004 - 2020) saw alot of use before I bought it and after, with minimal maintenance. Never had any failure, ever. Maybe sharpen the blades. The only reason why I replaced it was because the top of the deck rusted out and there were big holes. No weld shops willing or able to repair. It still works and I am damn tempted to hook it up tomorrow and try to get ahead of the growth we are having after all this rain. But it does throw up alot of stuff and probably isn't very safe. You think?
- No manual. I have a drawer full of nothing but manuals. I am a manual hoarder. I will look under deck tomorrow.
- I don't engage PTO at high RPMs. Isn't this a common sense thing?
- I don't mow at full speed through high grass. Again, common sense for so many reasons. I also don't mow at full throttle in C/3 through short grass. Once I am done mowing I have to work. I like plodding along.
- The bolt did not break elsewhere and then just eventually become dislodged. I have both pieces, the head and then the majority of the shaft, threads and nut (Pictures of both in my original post...), right there on the deck.
- No Clip. That I can see. What does this clip look like so I know what to look for?