Metal caps with wires soldered into place. Do not solder while the caps are on the motor. The bush housing is plastic and it will melt. Instead, remove the caps, hold them with a crocodile clip or similar and solder the wire into the groove. Ensure that no solder gets onto the inside of the cap - work from the outside. Try the caps in their correct positions without the brushes and springs. The bottom cap is the green wire and this has the tag to make an earth contact with the chassis. Note the method I use for keeping the springs from rolling away !