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> Education Resources > FAQs > Technical Service > Troubleshooting Thread Breaks Burrs or Scratches On The Rotary Hook

How do I troubleshoot thread breaks caused by burrs or scratches on the rotary hook?
Thread breaks are often caused by a scratch or burr on the rotary hook. This is likely the cause if you are having the problem on multiple needles on a particular head. The rotary hook doesn't have to be removed or adjusted to perform these steps. Remove the needle plate and the right side rotary hook cover. Turn the power off on the machine, the main shaft (degree wheel) can be rotated little by little from 100 to 220 degrees to have access to the outer areas of the rotary hook. Lightly rub your fingertip or fingernail along the outer edge to locate the burr. Any rough areas need to be polished smooth using very fine emery paper or sandpaper. 600 grit is recommended. If necessary, a more abrasive type may be used to polish a larger burr, however, be sure to follow that up with the very fine grit to ensure the area is smooth. Replace the cover and needle plate. Return the degree wheel to the red mark. Power on and test the machine.