Reassembly is tricky - make sure everything lines up including the switches and small circuit boards, which fit in lugs inside one half of the casing. Use a small torch to look inside if neccessary. Make sure cables are not "pinched". If everything is okay the casing halves should fit evenly and easily.

The second photo shows the reflector and bulb assembly for the top lamp. If you look closely on the right edge behind the bulb you will see a small metal "V" or claw - this holds the bulb in place. To remove the bulb, rotate it carefully so the claw clears the cutout in the flange and pull out.