The fact that the majority of the basic L tractors do not have the jerky 3 pt does not fit the story here. But it is a problem with some rigs though. If mine was that bad and still under warranty I'd raise holy hell until it was fixed!
Bluegill, if yours was that bad and out of warranty, you might take the same course. I know that many here would, particularly if they understood that just because a warranty has expired does not necessarily mean that the problem won't be fixed -- particularly under U.S. consumer protection laws.
What Burt and CaveCreekRay are saying is go to the wall, starting with the dealer, then Kubota's Rep, then Kubota's Customer Care, then your state attorney general
Certainly CCR's valve was addressed under warranty. However, note that it was at the bitter end of the warranty, and some of the parts
had no measurable or even discernible wear.
From this, a reasonable person, on examining a valve that exhibits such problems and seeing that it isn't worn, could see that the cause of the problem must be either a manufacturing defect or perhaps a design flaw.
Perhaps, as I suspect from reading this thread, many L38xx and L32xx owners haven't lifted 200# or greater loads with minute adjustments that CCR was making. If I had an L3xxx, I think I'd rush out and test mine. (Sadly,) I only have a B6100, and its 3PH problems are different.