Can you post the text printed on the label or any other ID.
It is probably two wires for the field coil and two wires for the armature.
Measure the resistance across each pair (should read open circuit if not a pair).
The higher resistance is probably the field coil(s) and the lower resistance (and noisier if you rotate shaft) should be the armature.
Just because it's DC most people assume it has a permanent magnet, but not always as I suspect is the case here.