JB Weld should work. Most likely the area to bond was not cleaned enough. These old Irons get oily and greasy and dirty, the bond surface need to be almost surgical clean for it to work. Also the mix (usually 50/50) should be adjusted to 60/40 with the extra on the hardener side.
The only other way I know of is to braze it. That is like welding but uses a lower temp and used bronze/brass rod to fuse the iron. (It is kinda like hot glue for metal)