Removing sheave from ISC motor-no space to fully lay motor parallel to the ground. The motor/frame were blocked from motion but sheave was hard to remove. EE was using impact wrench on sheave when the tapered bushing let loose & the wrench, sheave & EE's left hand were pulled approx 16"" downward. The wrench & sheave pinched the left pinky finger b/t the sheave & crusher structure.