While returning to Shanghai on 9 October, "Waller" fouled a Japanese-moored "Shanghai"-type contact mine. Three officers and 22 men were wounded, and the ship sustained enough structural damage to warrant a drydocking at Kiangnan Dock and Engineering Works at Shanghai. Following this period of repairs, the ship supervised minesweeping operations and supplied provisions and water to the ships engaged in the sweeps which netted some 60 mines. In addition, she provided Yangtze pilots for incoming vessels and monitored all shipping traffic passing her patrol station in the Yangtze estuary. The ship departed Chinese waters on 12 December bound for the United States, and after a stop at Pearl Harbor arrived at San Diego 18 days later.