I have a 9 year old TG1860 diesel with a 54 inch deck. Immediately on startup the steering wheel pulls hard left against the stop. When I disconnect the electric steering unit I can steer ok manually. The dealer has been no help except to estimate repair at $1100 for labor and a new steering unit. Kubota cust service says there are diagnostics available in a shop manual to diagnose the problem. Any recommendations from this group? Thanks in advance.