The proper removal wedges are not a universal solution. With some machines, there is little or no lip on the shaft adjacent the fat end of the taper onto which the proper wedge can bear. You see this on smaller Morse taper arbors with larger Jacobs tapers on them.
I have seen a soution to this which involves cross-drilling the tang on the arbor and using a pin through the hole against which a piece of tube can bear, the other end of the tube being a seating for the wedge.
At some point, it can be a better strategy to dismantle (destroy) the chuck in order to save the shaft.
There is no arbor, as I understand it. The JT6 male taper is on the end of the shaft: it reduces the manufacturing cost. It makes it a pain when you want to change the chuck, hence this thread.
The ball joint splitter is the wrong tool to use. Too steep a taper, pressing on one side only and against the wrong surface.
You need a pair of wedges to give an even downward force between the chuck and the end of the spindle.
I've had a couple of Katsu gear had no problem's.
as for my current drill I'm not going to mess on with it any more.
I'll take the motor off and what else might be useful and the rest to the scrap man.
All the help you have had on this thread and you still need a tenner, i give more than that to my binmen at Christmas. .
binmen must be pleased with you then eh.