hifi engine

Pioneer a-88x

Does anyone know how to remove the volume knob from the front panel. All other knobs pull right off. The knob has 2 small holes on the side and the schematic shows a "special nut" between the knob and the "volume assembly". I need this off to clean all the pods. service manual here:

Need Jumper Setting For Lost Voltage Selector Knob Pioneer A-88X

Found Pioneer A-88x at Goodwill missing voltage selector knob on back(Euro Version) - Can't find Euro schematic anywhere. Anyone know which wires are jumpered together for American voltage? Thanks