How much of a part do the pressure spheres play in suspension damping?

It appears, at least from the external shape, that the ABC struts have an integral spring.

One of my other cars is a '76 450SEL 6.9 - these cars came with full hydro-pneumatic suspensions, but the struts are only hydraulic rams, the pressure spheres are where all the damping is done. When a 6.9 needs new spheres, there's no mistaking it - the car rides like a forklift. The 6.9 service manuals indicate the spheres are a maintenance item and recommend periodic replacement.

I have no reference as to what this car should ride like when new, I got it with 100k+ miles. It does seem a bit stiff at times. I've not seen anything in documentation that suggests periodic servicing of the pressure spheres - just normal filter / flushing stuff for the ABC system.

I know I'm getting some "tire bounce" from the passenger rear tire - noticeable harshness if I hit a pothole or uneven pavement section on the right-rear of the car only. It feels like the tire is rebounding harshly and then bouncing when it recontacts the pavement.

Also - how many pressure spheres are there? I can see 2 up under the car in the rear, but I've not found any in the front. EPC says there are 2 "Air Reservoir - Pressure Accumulators" and 1 "Air Cell - Return", but it shows one of the Pressure Accumulators in the front and one in the rear, and the Air-Cell Return mid-chassis on the driver's side. I'm almost positive I saw 2 accumulators up under the rear of the car above the half-shafts, one on each side.

Any answers / suggestions are appreciated.