Had that problem a few years ago. Was out in the middle of nowhere when it broke and getting dark. I was sick most of the night wondering how to get that chunk of threaded shaft out. Small drill bit and a cordless drill, the shaft on mine drilled unbelievably easy. Stuck a small easy out in that I was sure to snap off and it threaded out with my fingers. Mine broke right on the shoulder of the threads and shaft taper so it took the pull or tension of the threads n was loose. Good luck. I would lay on your head  with a good pick and try to turn it first it might come right out. It is NOT reverse thread as some might say, If it was not broke you would put a wrench on top and pull to front of the machine, or counter clockwise.