Sorry, but hard to see from the pics and I’m not familiar with that type. One brush will be connected to the dynamo frame. The D connection should be to the other brush. There should be a connection (not to earth) that goes to a wire vanishing inside the outer coil – that is F. As suggested, a multimeter would be my first check. A good test is to connect D and F together and connect to 6V (try to get polarity correct to the intended machine) with the other connection to the dynamo frame) then it should run as a motor.
Keith
