I saw some axles broken when I worked on Deere's
almost every time there were spacers involved or the wheels were moved as far out as possible, and/or turned around. Similar, lots of front axle (MFWD) seal and bearing failures.
Many things can be involved. Y'all have addressed some of them already so I won't go into that part of it. But a question. Look at why spacers are installed in the first place. Do you think it's possible that the tractor is being used for something it wasn't designed for? I saw this often when I worked at the kubota place. Guys would buy a BX when they needed a D6, and they used their BX for a D6 and then pitch a fit because it wasn't built tough enough. If you look at how the BX is built, it is really nothing more than a glorified lawn mower which has all of the features of a full-sized tractor but in a VERY compact package. To get everything small enough, it had to be downsized which means compromises in "strength". So Billy Bob jumps on his BX23S and runs out onto his inherited farm (5 acres) to pull stumps with it. Guess what? The little tractor is unstable. So what's he gonna do? Spacers. More stable. Better yet load the tires and spacers. Now we can dig stumps with a bucket the size of a teaspoon. Breaks a 1/4" hose and then shows up at the dealer and wants a warranty hose. Or--should I say DEMANDS a hose under warranty. Then Billy Bob don't get his way because hoses are specific exclusions from warrantable repairs, so he posts all over the interwebs, and social media, that his tractor is a piece of junk, don't ever buy one and certainly don't buy one from the dealer.
Yeah I saw this stuff happen. And--one of the many reasons I used this forum, was because I had actually done a web search (from work at the time) regarding a customer's complaint of "this problem is all over the internet" (and by the way this was the only place I found reference to it), so I joined this and another forum. Here is the kicker. At the time I was actually working on a customer's tractor that had suffered engine failure due to overheat (radiator was plugged but the screen was clean)-and it was barely out of warranty not that it matters because plugged screens aren't warranty anyway. But on the other forum, I found the tractor's owner pitching a total fit about how the dealer (where I was working at the time) and the tractor manufacturer didn't stand behind their equipment, didn't honor their warranty, and were over priced-saying he could change an engine in his pickup truck in 3 to 4 hours. And just as I said, what he posted over there was not fully the truth which is extremely common in forums. So that in itself begs another question, how much of the BX axle breakage post was 100% truthful?