During the Aug. 30 spacewalk, Williams and Hoshide struggled to remove one of two bolts securing MBSU-1 to the truss. They prevailed, but found galling in the truss receptacle for the first bolt required to secure the replacement.

The spacewalkers used pliers and a nitrogen gas spray to unseat some of the debris. Nonetheless, the first bolt for the new MBSU jammed as they attempted to drive it with a power ratchet. As their planned 6.5-hr. spacewalk stretched to more than 8 hr., Williams and Hoshide were instructed to strap the box down without mating the electrical connections.

Aboard the station, the astronauts also worked to overcome a cooling system problem with Hoshide’s spacesuit.

The spacewalk was the first sponsored by NASA since July 2011. That outing coincided with NASA’s final shuttle flight and the end of the long-running assembly of the station’s U.S. segment.