In this video I extract the broken shaft from the socket head cap screw (12 mm x 60 mm). I found it when I heard the transverse bar making a chiming sound when a ball hit the impact strip. You can locate many issues if you trust your ears. The broken threaded part is stuck inside the bearing block. I used a small drill bit to make a guide hole for the larger drill bit. I did this to assure placement as to not ruin any threads in the bearing block. Use cooling oil and take your time.