1.   But shuttle managers were reluctant to proceed with additions to the solar power system without replacing the primary wrist joint assembly.

2.   However, in early March the arm experienced what experts believe was an electrical short in its wrist joint assembly.

3.   In early March, the device experienced what ground-based experts believe was an electrical short in the wrist assembly, which momentarily immobilized the entire limb.

4.   The robotic device has been working with a backup wrist assembly, but station managers want to restore the primary mechanism before they embark on major assembly activities.