Employee was separating shim packs for upper bearing on main rotator of swing case #4 of a Marion 8750 Dragline. After heating the laminated shims, he was using a putty knife to work the shims apart. The putty knife caught and pushed the shim pack, slicing though his gloved hand causing a laceration to his left thumb and a cut tendon. *A 7% whole person impairment was issued.