Since it's been broken & brazed or silver soldered once,,TIG'd and broken once,,and it looks like maybe the tip of the stem was also built up with some weld,,,,I'd cut the entire back half of the stem off.
That'd get you to the thicker forward portion with no old repairs, welds, stresses or needed relief cuts in it.
Splice in a new section there using a overlapping joint for strength and braze it together.
Then recut the back end to match the old profile of notches ect and half round the stem of course.
Use the ejector from the other side as a guide for the profile as well as pics and quick drawings of this broken one.