Winco if it is the 2 bearing type/ its not hard to work on.. Usually its the rectifier or the diode that has gone bad.. If its the Armature you might as well trash it .. The armature cost as much as the generator head// I see the 2400 watt heads on ebay sometimes running about 375.00.. You can also get a voltmaster from Northern Tool for about 400.00/// Beore I spent any money on it I would take it to someone that has a growler and have it tested .