My john deere is not charging what is the problem

Hi,
Can be the atternator (only slightly likely , if the magnets have "scrubbed it), the rectifier (more likely) or bad connections at the battery (also likely if you see blue-white corrosion.) Try the JDParts site at:
John Deere - Parts Catalog (http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePa geServlet_Alt)
Peace,
Clarke