2013 Mercedes Sprinter EGR valve cleaning procedure, do every 15,000 20,000 mi, stops coughing

Mercedes factory repair procedure replaces clogged and sticky EGR valves when they get gunked up with carbon. I have been cleaning mine every 15k mi or so since it started bucking and coughing around 32k mi. And it has been a reliable preventive maintenance. Around 90k mi the servo motor went bad and I replaced the whole unit. But by 90k miles most people are on their third or fourth valve! It’s super easy to clean. Here’s how.