Hi, when looking directly at the brush end of the dynamo, there are two brushes, and two wires exiting from the field coil lead holes. With the field coil lead holes at the top the right brush goes to 'D' and the left brush goes to the earth stud (little screw above the bearing) where the right field coil lead is also attached. The left field coil lead goes to 'F'. This is the usual arrangemet though other arrangemets will work if the dynamo has been apart and things have been altered. If the dynamo is not working you can try flashing the live side of your battery on the 'F' terminal. You can also try swapping the field coil leads over. If the dynamo was working and is now not working maybe the brushes have have got worn or stuck.