Removing the plastic chassis from the metal chassis. Make sure that the gearbox pin has been removed and turn the chassis upside down so that it rests on the bulb housing and the rear block. The contact washer for the bogies is soldered to the contact strip on the right side of the loco. This needs to be gently eased off its plastic washer, and bent upwards, so that it doesn't get in the way. Don't lose the plastic insulating washer.