Spinning wheels serve two functions. First, the spinning of the flyer imparts twist in the fiber to create yarn. Second, the spinning energy is also used to wind the spun yarn onto the bobbin. Usually this works like clockwork, but then there are those times when the yarn will not wind onto the bobbin. Take up problems can be the result of a variety of different causes. Some are easily remedied, while others take some work to fix.
Begin by checking your method. Are you letting the tension ease enough to permit the yarn to wind on? If you have just begun a new bobbin, be sure that your leader yarn is wrapped around the bobbin several times in the proper direction. Clockwise for singles, and counterclockwise for plying.
The most common culprit in my experience is caused by a few fibers wrapping around the flyer hooks and creating just enough of a barrier that the yarn cannot advance past it. In most cases, this can be easily fixed by simply cleaning the hooks by hand. If the tangle is larger, or it spans several hooks, it is sometimes more thoroughly cleared with the threading hook.
If the flyer teeth arenít clogged with stray fibers, the next symptom I check for is that debris hasnít built up on the inside of the bobbin. Unless you spin very fine fibers, or prefer spinning in the grease, this is a problem that occurs quite infrequently, but it is still a much less drastic repair than replacing a drive band. To clear the bobbin core, run a pipe cleaner through the opening a few times, or wrap a scrap of cloth around the spindle and use that to clean the inside of the bobbin.
Take up difficulty can also be caused by tension problems. If the wheel is not tensioned properly, the bobbin will not take up when the drafting pressure is eased. First check the drive band to be certain that the tension on the band is not slack. It should be firm enough to resonate a bit when plucked, but not so firm that you hear a sound when you pluck it. If you have exhausted the range of the tension knob, you will have to construct a new drive band. Be sure to release the tension completely before fitting the new drive band to permit maximum usefulness of the new band.
On a wheel that has scotch tension, take up can be difficult if there is not enough tension on the brake band. This can be caused if the spring has become worn, or if the brake band has stretched. Increase the tension on the knob, or replace the brake band as needed.