[Kurt in NJ]

sparkley can come from several places it can be solder thrown from the commutator(usually that is a line all around ) it can be grindings from armature rubbing on the field shoes (there will be marks)-wires rubbed, brush holders rubbing wrong places and possibly brushes themselves-originally that style generator would have the field ground wire brought out of the case along with the power wire so it can be used to connect to the regulator part of the oval cutout.
it looks to be cobbled up with regular primary wire, originally it would be a high strand count very flexible wire cloth covered.
many growlers also had a 110 volt 'test light', this was used to test for grounding of windings, if the light lit there was a ground, if there was weakness in the insulation there could be smoke, this gives you a place to look, clean ,shove a piece of insulating paper in