Jammed meters are viewed as a lucky break by local drivers who figure they’ll enjoy a free hour or so of parking until the city repairs the machines. Turns out the problem is usually not mechanical but the gleeful mischief of U-M students who prefer their spare change go to Starbucks, not the city’s coffers. Recently, a parking enforcement staffer used a small knife to remove a nickel jammed in a meter at the Fourth and Catherine lot. He showed a curious pedestrian how the nickel had been deliberately dented to stick in the machine. “Happens about ten to fifteen times a month,” said the official, resigned. “More on campus. It’s the students.” Unless the kids are caught in the act, he explained, “there’s nothing we can do.” Innocent or guilty, those who park at the plugged meters get a grace period (two hours) after the nasty nickels are removed.