In that case check if the seat switch is NO or NC then either jump the terminals or unplug it to fein you being in the seat
Problem goes away = bad seat switch
Because I am a tech, I have a set of plugs so I can power the PTOs independently of the mowers wiring that I use for the purpose of diagnosis
I also have a set of seat switch bypass jumpers for the same reason but none for Kubotas because there is only 2 in my service run .