So i purchased a very old asplundh wood chipper. i believe its called the basic model, whatever that is. It has a 4 cylider, no blower on chute, and 12" drum. Can't find a tag with serial number on it. Maybe one of you has ran across one like this. Would like to get a manual on it if possible. Also are these old chippers 6 or 12 volt? And are they positive ground?