A secret a friend told me was to put 1 tablespoon of vinegar for every 2 1/2 cups flour. The vinegar doesn't taste in the final product and it seems to allow the gluten strands to develop. Add it after the first cup of flour has been added. I have never used a bread machine but it sure helps when I make it from scratch and by hand. I have never waited to add the vinegar that I remember but maybe it works better that way.
Lynda