I did it! I made a soymilk that was free of unpleasant grittiness with the right amount of salt and sweetness. Now I shall jot down my notes so I can remember it next time.
Make soymilk in machine according to instructions. 1/2 of a rice cup of dried soybeans works out well for a single batch (75 grams according to manufacturer's directions). Fill water to JUST above the bottom line. After it is done, strain through muslin cloth to remove residual grit. Add the following and boil for a few minutes. Cool to room temperature and refrigerate.
Two batches of soymilk
1/3 cup sugar (and a dash more perhaps)
1/4 tsp salt