JimR: From your posts and comments, we all know your situation with the fuel injector problem. That a fuel injector was delivering 150% of required fuel, which overwhelmed the emissions system and fully plugged the DPF.
I was talking with a Kubota dealer last week, and just like Kioti, they also use a laptop for complete engine diagnostics, view system control settings and can even do a forced regen from the laptop. They can determine the amount of fuel each cylinder receives, and even override and adjust the fuel accordingly.
Is it possible, that somewhere a Kioti technician accidentally and without knowing it, adjusted the fuel injection level to 150% thus creating the problems you experienced with your DPF emissions system. These laptops can be dangerous in the hands of a poorly trained technician.