I have just bought a Kubota T1670 ride on with a 40inch cutting deck, and a Kohler 15hp motor. I have had a few problems with the machine. The day that it was delivered the Spark plug was faulty. That was fixed on the same day. Two weeks later the cutting deck is faulty. I can't move the deck up and down. I have had a look under the mower, and the nut that connects the deck height lever to the actuator has come off. I would like to know if there should be a locking nut on there, or a standard nut with a spring washer. I would like some technical drawings of this mower, or just of the deck activation systems. Hope you can help.