Problem solved, after several calls to the factory and the help of two dealer techs. Several hours of head scratching led one of the techs to unhook the wire guidance manager and the issue went away. Apparently, even with the switch turned off, the guidance was still trying to control the steering whenever the machine would change direction, but only for a split second. Oh well, I will have to keep notes on this one, another first after 18 years on the job.