Symptom

• The upper thread appears as a single continuous line.
• The lower thread is visible from the upper side of the fabric. (Refer to the illustration below.)
• The upper thread has tightened up, and comes out when pulled.
• The upper thread has tightened up, and wrinkles appear in the fabric.
• The upper thread tension is tight, and the results do not change even after the thread tension is adjusted.

Cause

If the lower thread is incorrectly threaded, instead of the appropriate tension being applied to the lower thread, it is pulled through the fabric when the upper thread is pulled up. For this reason, the thread is visible from the upper side of the fabric.

Remedy/check details

Correctly install the lower thread according to the following procedure.

1. Turn off the sewing machine.

    

2. Slide the button and open the cover.
   

   (1) Cover (2) Slide button

3. Remove the bobbin from the bobbin case.

    

4. Put the bobbin in so the thread comes out in the direction shown by the arrow.

    

   

   Make sure you set the bobbin so the thread unrolls in the right direction. If the thread unrolls in the wrong direction, it may cause the thread tension to be incorrect or break the needle.

    

5. Hold the end of the thread, push the bobbin down with your finger, and then pass the thread through the slit, as shown.

   (1) Tension-adjusting spring

6. Replace the bobbin cover.
   Put the left tab in place (see arrow A), and then press lightly on the right side (see arrow B) until the cover clicks into place.
   
   
   
   

   Replace the cover so that the end of the thread comes out from the left side of the cover (as shown by the line in the diagram).