Have you used the correct stabilizer? That could also affect your embroidery,especially if it is a dence letter. The smaller the letters are, the least dence they should be. I hope that stabilizing in a different way may be the solution. ****
you can use the same color bobbin but first try lower the tension of the upperthread.
Try loosening your thread tension, if it is 2.5 make it 2 or 1.5 that should help. Did you decrease the size of a larger font? Or is it a built in font on your machine, is this the original size of the fontP It could be the digitizing. But usually it is the tension. Hope this helps til others can give better info. Linda
I am going to try this the next time I do small letter. Right now I have just been avoiding them. Thanks