A crew was removing and replacing shafts/rolls on a conveyor using an overhead crane. A roll did not fit correctly and needed to be repositioned. A wire rope choker was positioned in a basket configuration around the shaft/roll with the ends of the choker connected to the crane hook. The injured employee was holding the top legs of the choker as the operator lifted up on the hook to put tension on the choker. While the employee was holding the choker legs, the crane hook started to twist. His left hand and glove became tangled between the steel choker legs. His left index finger was stuck between the choker legs, resulting in a distal phalanx amputation.