Yep the weight is missing. It could be that it either "fell" off or a previous owner removed it to stop the system from functioning. Only you will be able to verify if it is functioning properly, but let me suggest a test. First lubricate the lever pivot point. If it's been inactive for a while it might need a bit of help.
When it's dark, park opposite a wall or other vertical surface (Garage door) Put your headlamp selector twist switch (Left hand stalk) onto Auto.
Turn on the ignition, start the engine and watch the lights ahead. They should lower whilst the system adjusts for the weight distribution in the car and then raise again to a working level.
If this happens then the system is working correctly.
An advance test is to do the same again and mark the settled level of the light on the vertical surface as a reference point.
Then load the boot up with something very heavy, or alternatively get another person to sit over the rear bumper with the hatchback open.
Then repeat the above. The lights should activate in the same manner and adjust to settle at the same (or near enough) level as before, compensating for the extra weight.
