An employee was cleaning grease from the front hydraulic coupling hoses of a wheel loader to align the holes and coupling pins manually. Once the coupling pins were aligned, the system's hydraulic system was ready for testing. A second employee climbed into the wheel loader's cab as the first employee examined the pins. The second employee turned the wheel loader key, which automatically engaged the pins. At the same time, the first employee tried to clear out some additional grease from the coupling hole. The first employee's right middle finger was crushed at the nail bed by the hydraulic pin, resulting in amputation of the right middle finger at the nail bed.