An employee was troubleshooting a product non-conformance. While doing so, the employee suspected that the machine (tapering mill) had been set up or repaired incorrectly. After turning off the work cell, which this machine is a part of, the employee entered the work cell to verify the machine was set up correctly. The employee was attempting to adjust the machine's tapering rollers when four left-hand fingers were caught and fractured in between the rollers.