Don't know about the joints on your cutter but I've installed hundreds of u-joints on various other things. I never "pressed" the old joints out and I'm not sure if you can.
I've always driven the old joints out with a hammer and a chisel. Put the chisel against the cross of the joint and drive the bearing cup out on one side. Then go the other direction and drive the bearing cup out of the other side. Then the joint will come out.
Press the new bearing cups in on the new joint using a bench vise or, if you can't get it in a vise, with a large C clamp.