Federal, state and Port Authority investigators were examining Thursday the operation of the window-washing rig which suddenly malfunctioned Wednesday and led to a heart-stopping rescue of two workers some 700 feet above ground at 1 World Trade Center.

The probe of the rigging continued as other workers repaired the window on the 68th floor, which had to be cut open by FDNY rescuers so the window washers could be pulled from the dangling platform to safety inside the tallest building in the Western Hemisphere.

Juan Lizama, 41, of New Jersey, and Juan Lopez, 33, of the Bronx, suffered only mild hypothermia after dangling for about 90 minutes in the wind, officials said. They were secured to the building by a special climbing rope passed down to them from firefighters on the roof of the 1,776-foot tower. Both men are expected to speak to reporters in Manhattan Friday about the ordeal.

A rig maintained by the company that provided the one at the World Trade Center fell in a horrific December 2007 accident in which two window washers plummeted 47 stories at a building at 265 E. 66th St. in Manhattan. Edgar Moreno died and his brother Alcides was severely injured. In a lawsuit filed by Alcides Moreno, evidence surfaced that one cable wasn't properly crimped. The suit was settled in 2010 for an undisclosed sum, court records show. Officials at Tractel in Canada declined to comment Thursday.

Port Authority officials would only say Thursday the investigation into the mishap continued and the state Labor Department also was involved. A spokesman for the federal Occupational Safety and Health Administration said the agency also was investigating.

John McDermott, president of Upgrade Services, which employed the two window washers, said Wednesday in a statement "the cause of the incident appears to be equipment failure of the traction hoist brake mechanism that supports one side of the rig. . . . This caused the scaffold to drift into an almost vertical position, leaving our men stranded until a rescue could be performed."

Patrick Foye, executive director of the Port Authority, said Wednesday the rig was inspected by the state in June.

With Darran Simon,

Maria Alvarez and amNewYork