CAPE CANAVERAL, Fla. -- The International Space Station's Canadian robot arm has a new, fully functioning wrist joint thanks to a successful orbital house call Thursday by a pair of spacewalking surgeons.

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The good news came a little more than half-way through a seven-hour and 17-minute excursion outside by Endeavour astronauts Franklin Chang-Diaz and Philippe Perrin. It was their third spacewalk of the mission.

The pair first removed the robot arm's "hand" and then it's faulty wrist roll joint, which hadn't been working right for more than two months due to a failure believed to be in some electronics.

Chang-Diaz and Perrin stowed the old joint in Endeavour's cargo bay, retrieved the new unit and then installed it at the end of the arm. That was followed by the reattachment of the end-effector hand.

Managing the spacewalk from inside the shuttle, Endeavour pilot Paul Lockhart then told flight controllers in Houston it was OK to restore electricity to the crane.

"You have a go to power up the station arm," Lockhart radioed to Mission Control.

"OK, Endeavour, we copy," astronaut Mike Fossum responded from Houston. "It's time to wake up the patient and see how the arm's doing after surgery."

After completing an initial set of post operative tests to make sure the new joint was working as expected, NASA officials said it appeared the patient was healed.

"I think this mission is truly on the brink of being added to NASA's list of success stories," said station flight director Rick LaBrode.

For NASA, the achievement was especially sweet as it was completed just 85 days after mission managers approved adding the spacewalk to the mission -- a relatively last-minute call for a space agency used to planning and training months and years ahead of time.

Working overtime to train the crew, install the replacement hardware in Endeavour's cargo bay and assemble a new mission plan, the combined shuttle and station workforce was able to accommodate the change and pull off the operation.

"It compressed everyone's schedule but when it's this important, and when it affects this many downrange flights, it was the right decision," said Tricia Mack, NASA's lead spacewalk officer for this shuttle mission.

On Friday the combined station and shuttle crews are to remove the Leonardo supply module and stow it back in Endeavour's cargo bay.

Saturday the shuttle is to undock from the laboratory complex.

Landing of Endeavour back at the Kennedy Space Center is now targeted for 1 p.m. (1700 GMT) Monday.