I cleaned both areas with solvent. No pin thru the shaft or handle hub could be found. I took a file and went inside the hub and all I could see was bright steel. The brass washer between the hub and vice jaw had a slight rough edge on the inside edge which at one time could have been a shoulder . I can see some small what looks like a weld pattern on the inside edge of the hub. My thoughts on brazing is the thick parts may effect the heat treatment as this area will have to get hot to melt the rod. On the other hand a recess and stick weld may not heat up the shaft as much. as the weld could be completed in sections and cooled before re starting.