Well, it's cracked. How bad is it?

Take your time and you will get the results you want. I would want to relieve the tension the dip stick tube has on the inner hole of the block. One of the pictures shows what is left of old dip stick tube outside of the block, start here using a SMALL chisel or screw driver. Chisel what is left of the dip stick in towards the center of the tube hole, if you take your time you may have enough metal to fully close the tube shut. Using a metal rod small diameter lightly hammer up ward toward what you have mushroom earlier. This works. Also I have used an hacksaw blade to cut the tube to relieve the tension. How, break the blade long ways it will "snap in half" take the blade clamp it in the vise and hammer the blade and "snap" you now have a cutting tool about 3" long and 1/8 wide with teeth, this will allow you to hack saw the tube out of the block. Relieve the tension! As far as the crack nothing to pull your hair out, take needle nose pliers or duck bill pliers grasp the skinny side of the crack give it a wiggle as much or a little YOU feel OK with. If it wiggles, break it off, solid just leave it alone. Hope this helps