Once all personnel were in the sphere, the CO2 scrubber was powered up. At low speed it seemed to be drawing little air, and at high speed flow was satisfactory, but the motor was lugging. However, after some tests it was decided to dive with the blower running at high speed. CO2 continued to rise in the atmosphere and within several hundred feet of the surface the blower motor failed. Permission to surface was sought and two weights dropped to stopped descent. Shortly thereafter two other weights were dropped. EBAs were donned when CO2 reached 0.8%. Within a few minutes the oxygen alarm sounded, presumably due to a leaking EBA. The UQC was secured and EBAs removed to allow personnel to consume the excess oxygen. The sub was recovered normally and the hatch opened; by this time the CO2 level had reached 2.3%. Matt did an extraordinary job handling the emergency, showing great poise in making correct decisions to respond to a rapidly evolving situation.