To the OP. When the tractor is on a hill does it continue to roll down the hill with the brakes off but the HST is in stopped position ? If its on flat ground can it be pushed and have the wheels move? The problem you are having can't happen with a correctly operating HST. Its all about fluid flow to make the machine go, right? All the lever does it change flow of the fluid, faster slower front back. When its in neutral no fluid should be able to move so the wheels can't move. This older thread, even talks about the older
bx24 tells you that if you have the HST in stop it can't move nor can it be moved.
http://www.mytractorforum.com/76-cu...ompact-tractors/163871-kubota-push-towed.html
I had an issue with my JD 30+ years ago. The valve froze (rusted shut more like it) and I had a **** of time moving the machine. So to me, and I don't doubt you have some kind of issue, for some reason you must have some kind of 'internal fluid leak' between the pedal and the neutral setting on your gear. If I understand it correctly when you put kubota's in neutral you can tow them...is that correct? That would be the same as the valve I used. To me that is one way the machine could keep moving even when the pedal has it at stop. It appears its not a lot of fluid just enough to not stop immediately. The other is that some way the fluid is allowed to flow thru the valve controlled by the foot control, I can't fathom that one but hey anything is possible.
Or do I have this all wrong? Lets be honest this is serious safety issue. Other than steering or parked (actually I often forget) I don't use brakes on an hst because it just stops the machine. Frankly I remember wishing it would coast down some hills to make it go faster but it couldn't do that (I was younger and more foolish then) because of HST. Anyway my two cents to try to help.