have you got the sector arms off?
they have to come off
the adjusters are studs in a slip fitting on the sector
the sector gear and cover exit out the same path.. which is why the sector arms must be off the other side.
i've marked up a drawing of the steering box on a 640
the side covers have a lip inside .. it may be siezed a pit. tap on the ears to rotate them and get themmoving.
penetrant will help.. just pull them and the adjusters togeter dragging the secrtor gear out. if they are seized it will be the easiest way..