I can't seem to find my users manual for my machine. I am having trouble with the pressure foot being too tight. When I try to sew a satiny type of material, the bottom layer of the fabric keeps stretching so that when I get to the end of the seam I am sewing, I am left with a huge amount of material that shouldn't be there. I am guessing that it's because of the pressure foot, and I don't know how to loosen it up without my manual. Can you please help?