An employee was unpacking and removing wrap and bands from pallets of wheels. While removing a piece of plywood (39 pounds and 4'x4') from a stack of wheels, the employee lifted the pallet up on the right side, allowing the plywood to slide down the left side between the pallet and the walkway guard rail. The employee went to stop the plywood from hitting the conveyor guard when their little finger was crushed and amputated between the plywood and machine guard.