I generally use full strength AWESOME! cleanser since it's cheap. I spray it on and work the stem with wet/dry sandpaper. Depending on the oxidation, I will use 400,600 or 800 grit paper. Elbow grease. That usually cuts through the worst of it. After that, each stem gets worked over with my Dremel tool with a yellow polishing wheel and Tripoli compound. I know you said you had no power tools, but the above is a small investment that, for me, has paid for itself. Most of the pipes I get in my workshop are green with oxidation. Good luck!