To clean the gas pistons and gas block, the tubes are removed with a 3/8-inch open-end wrench. Then the two pistons drop out, you clean 'em and swab out the gas block, put it all back together, and you're done.
My dad's excavation had uncovered a sickle with a hand-carved, hand-riveted grip; some harness parts; a 4-foot float level; and a spectacular variety of wrenches, including a leviathan open-end wrench nearly 3 feet long and weighing about 10 pounds.
The editorial staff was armed with a socket wrench, but it would've taken much less time with an open-end wrench. We thought the instructions needed a bit more emphasis in certain places (bolts should be loosened, but not removed all the way, which we discovered too late).