Well my 300td/1983 would have passed the 'bounce it and see one return' test but when driving the ride seemed underdamped. I also had a bad rattle from one side/rear and a leaking shock absorber. I removed both spheres - one was full of fluid - broken seal. One worn plastic link between anti-roll bar and suspension arm was the cause of the noise. So, it's still not clear to me how to test spheres with the eloborate pressure gages & valves described in the manual. Whilst removal and inspection can detect broken sphere it can't detect spheres that are partially 'shagged'!