A subway station elevator on the Upper West Side has been out of service for months, and one fed-up mom turned to social media to try to get help. Back in December, both elevators at the 72nd Street subway station were closed down to install new ones, and the timeline has struck a chord with commuters. The MTA says the elevators will be running again in July, but that feels far for Katie Knuhtsen, who demonstrated the difficulty she faces trudging up and down two flights of stairs with a strolle