Shot in the dark - you could try Johnson Harvetsting. They advertise many new and used parts for those series machines. Evensville Mn. http://www.johnsonharvesting.com/
There are other custom harvesters in Mn, that could have one around also ? Holland Harvesting, Litchfield Mn is another one.  http://www.hollandharvesting.com/index.php?option=com_content&view=article&id=44&Itemid=1