There are a couple of kind of "Nutserts" out there. There are the ones that have a small diameter expansion and then there are the ones that spread out a lot.
Here is a pic of the large flange type:
Split Side Nutsert
You could always just drill out the spot welds on the bracket and put a new stud in there. That's harder though. Nutsert is probably the best way to go.
Be careful and don't drill a hole through the floor.