Removing a suspension sphere
The proper Citroën workshop manual method—in contrast to what the Haynes manual says—is to loosen the suspension sphere with a chain wrench ¼ turn while the system is still under pressure. Be very careful and absolutely sure that it is really only by a quarter of a turn. The pressure in the system is huge (the force behind the sphere can reach more than one ton, that is several thousand pounds), so opening it up with all that high pressure liquid behind it can be extremely dangerous.
Sometimes this is easier said than done. Strong chain wrenches usually do the job but a cold chisel and a hammer can also be used to hit the sphere tangentially. This leaves marks but generally breaks the corrosion between the sphere and its support. And here is a nice idea from Alasdair MACKINTOSH: "My home-made sphere remover consists of a large jubilee clip and a piece of old bicycle inner tube. Choose a clip that's big enough to go round the sphere. Wrap the piece of inner tube round the sphere, then fit the hose-clip round the sphere, along its 'equator'. Tighten up the clip, then place a big screwdriver in the screw, and whack the end of the screwdriver with a big hammer. Make sure that the inner tube rubber is clean and dry, and does not have any remnants of talcum powder on it. Also make sure that the screw head on the clip is facing the right direction to loosen the sphere when you put the screwdriver in its head."
Then, undo the pressure release screw on the pressure regulator (in front of the engine, at the bottom) by 1 to 1.5 turns (don't remove it!) and move the height control lever in the cabin to the lowest position. Now you can loosen the sphere completely.
When you fit the new sphere, grease the mating face of the support and tighten the sphere only by hand as recommended by Citroën. You will be able to remove it easier next time.