Is it graphite or fiberglass? If graphite, it probably can't be fixed. If glass, you might be able to take section of another broken rod, cut a 3-4" section that will be a good slide fit inside the blank and epoxy it inside the blank. Then wrap over the repair area and epoxy over the repair wrap. Sometimes this will work if the blank is not cracked, but you will always have a stiff place where the repair is made.