I can't explain it either....if it was a faulty design, seems like all the MX / L's would have the same problem. If it was faulty parts or workmanship, it would seem that replacing parts or identifying a fix would be possible. Only solutions I have seen are more of a work around instead of an actual identification of the problem and definitive fix.
Hard to explain for a company like Kubota
And that is the part that ticks me off the worst..
Anyway, like pmhowe said, I'd only get another MX5100 if you can try it first. Interesting odds, 1 in 10. Not something I'd bet $20K ++ on. No point in ordering one if it might be the same problem in my opinion.
I'm guessing they haven't given you the option to simply return your money, only the "buy a different Kubota tractor" avenue? At the risk of sounding like a conspiracy theorist, which I'm really not, it's like they're luring us in with the "cheap" tractors. Then when we discover there's a problem, the only way out is to spend more money on an upgrade. I'm not suggesting you do this, but I'd be interested to see what a good lawyer (is there such a thing?) could do with that in court.
Ok, enough spite from me.. if there's an explanation as to why some are better than others, I think a lot of it is the owner's expectations. What I consider jerky another owner might be happy with. Have you seen the Youtube videos I posted of mine?
I think some of the problem with them is the amount of free play/lost motion in the valve linkage under the transmission cover. If it was a simple hydraulic valve with no position control I think it'd be fine, but there is enough slop in the linkages that the 3pt can move quite a bit before the feedback linkage closes the valve again. I thought briefly about trying to spring load the linkage inside the tranny, but I had visions of a spring getting loose among the gears and decided it wasn't worth the risk.
You can probably smooth it out quite a bit by adding a flow control valve to the mix for about $100, like smweatherman did. They're on sale this week locally, it reminded me of this whole thing again.
Like the guys have said, I've not heard of any of the Grand L's having this problem to any degree at all. Good luck and keep us posted!
Sean