Deploying last hour's fix, #631, left the robot with no motor services at all; the joint-state publisher wrote joint_names, a field sensor_msgs/JointState does not have, and the code had never run because the sweep never returned data before. They also measured the broadcast read at 54 ms with only 24 of 26 servos answering, so per-servo reads at 15 ms are now the only path.