A postal worker’s arm was amputated after an incident at a North Carolina mail center that’s accused of recurring safety violations, federal officials said. A mechanic at a distribution center in Greensboro was severely injured by “a machine that had a safety guard removed” in September 2021, according to the U.S. Department of Labor. The worker’s arm was amputated after the injury, officials said. Months later, the U.S. Postal Service faces $170,918 in possible fines. The labor department said it conducted an investigation into the injury and found the Greensboro workplace had “repeat and ser…