I have that problem too. What I do is I fill the spindle as much as I can, then I unroll it into a ball. Then I start over, when I have filled it again I hold the ball from the previous time over the spindle, fluff the ends a little, then combine them by spinning the end from the ball and the end from the stuff on the spindle together. You can't see the spot once you have done it, the seam disapears. I don't know if I explained it so you can understand it, but I hope that will help. If you need, I could make a video of myself doing it.
"All it takes for evil to prosper, is for good men to do nothing"