The bobbin sensor in an embroidery machine tells the user when the bobbin thread is low. If the bobbin sensor on your embroidery machine no longer works, first check that the bobbin is the correct type for the machine.
Next, clean the bobbin sensor. Remove the bobbin. Clean out any lint in the bobbin area. Behind the bobbin area, there is a sensor. When lint accumulates on the sensor, then the bobbin sensor can not tell how much thread is left on the bobbin.
Watch the video to learn how to clean the bobbin sensor in an embroidery machine.
Check out our other videos on cleaning the bobbin rotary hook and cleaning and setting bobbin tension.