Hello Teresa, First, you can get the yoke welded to repair it. Take it to someone who welds cast iron, and they will heat the entire thing, then weld it with cast iron rod and an acetyline torch. The yoke will need to be removed from the bell first. A less attractive, but also less expensive repair is to have it brazed. Brazing will leave a big bulge at the point of the repair, while the first method will not.
You can buy them from Prindle Station our of Washington State., Just do search or go to http://www.prindlestation.com they will either help you find parts or they will sell parts that will fit your bell.