The problem could also be a noisy whorl. To determine if the noise is coming from the bobbin or the whorl, place the drive band (or bands) first over the whorl and treadle. If the whorl makes a noise, then the source of the noise is the whorl. Now place the drive band over the bobbin and treadle. If the bobbin makes a noise, then the noise is coming from the bobbin. To fix whorl noise, the flyer and all whorls should be sent to Schacht for tightening. Noisy bobbins should receive the treatment noted above. Climatic changes may cause a bobbin to become noisy. Also, bobbins may become noisy when they are very full.