['LIVEWIRE?']

All I can think of is that, besides the motor pulley having two grooves one above the other, is that the grooves on the two flywheels are in different positions, one nearer the bearing end, the other nearer the spindle end. This is supposed to allow the belts to be routed so that they run correctly. Thus the belt which is routed around the lower of the two grooves in the pulley should go around the flywheel whose groove is lower down, and vice-versa.