The guy will need a good machine and really know what he is doing if he is going to use a mig machine.  Do not let him touch it if he has one of the little 110 volt machines or is using flux cored wire. 

You can tig the crack or weld it with a torch.  It will probably crack again in that area because the bracket design and location of the bracket was not optimized or tested for durability as proven by the high number of repeated failures in this area.