There are 4 hydrogen spheres that is the actual suspension. Basically the suspension consists of 4 spheres, 4 hydraulic cylinders, some valves and some solenoids.
The Spheres seem to have a lifespan of roughly 100 000 km, they are not fixable, you replace them. It is a sphere with a membrane in, on one side hydraulic fluid, on the other hydrogen, this is the shock absorber. When it fails, the membrane is broken, the sphere fills with hydraulic fluid and the suspension is not stiff, it is rock hard.
If fluidlevel drops in the reservoir (next to the washer reservoir) there is either a leak in the system och one or more spheres gone bad:
If the reservoir is empty, do not turn the engine on, this might damage the hydraulic pump as it will get air sucked into it and not fluid.
There is absolutely no danger of running a car with broken spheres as long as there is enough fluid in the system, although, the car is almost not drivable, it will bounce horribly.
Some new and old spheres:
I bought these: