Headlamp levelling motor
 

Hi People, new to this forum. Have a 93 Vector convertible, 07 plate, the headlamp levelling motor ( Halogen lights) doesn't appear to be working on the Drivers side headlamp,. I've got the bumper off, the headlamp off, and I can hear the motor going, but it's behind the passenger (left) side headlamp. Can anyone explain how the motor on the left makes the headlamp on the right move! I can't see which parts are supposed to move or how! Do I need to replace complete headlamp unit, or could it be something else. These are not self levelling lights, it's the one that's operated from headlamp switch on right of the dashboard.
Any help appreciated please.