Ball joint doesn’t want to get off the drive shaft

I’m still going crazy with this Audi ! The replacement of the drive cuffs at a 95er B4 2.o artet in madness. Now I did a lot of work after hours of shouting in with WD40 and hammering – but now the drive shaft joint at the front doesn’t want to get off the shaft! The cross handlebar is on the ground, is out of the way and I held the shaft with a man and tried to knock down the joint even with a plastic hammer. No chance! The fat central screw is of course already outside (o; Is this thing still secured somehow? Or what do I have to do to make it loose…? Greetings Kenny *so a screwdriver car it the B4 really not!*