Brazing does leave some to be desired, I'd bet the guy did it without knowing about the clay bed trick based on the open joints.
His buildup on the outside says it's been done twice, probably failed when he just brazed the pieces together so he piled on a couple big rods.
Why it was rebuilt instead of replaced, might have been the only tool of that kind in town, or it might have been saved from the scrap bin by somebody who wanted his own and figured he could braze it back together.
Rusty I totally disagree with your estimate of heat input and stress cracks. That job didn't need to go over 1700° and more likely was done under 1300°.