An employee working on a core machine in the core room had the right pinkie finger amputated as a result of injury. The spreader box stopped indexing across the carrier. The employee went around to the back side of the core machine and noticed that the dowel pin had broke and the back spreader box support wheel was dislodged from the rail and appeared stuck. The employee pushed on the bracket just behind the wheel to try to get the spreader box back on rails and the wheel shattered. The pressurized cylinder snapped forward and caught his pinkie and ring finger on the right hand. The right pinkie finger was surgically amputated.