Originally Posted by
charsuewilson
Mine's supposed to tell me, but it doesn't always. The only way to tell is looking at the stitches, and seeing none.
Sometimes my machine will fail to indicate low bobbin, and it's always due to a film of dust/lint over the sensor light, which is a tiny bubble light on the inside of the door. The lint prevents the light from shining through the bobbin and hitting the light sensor behind the bobbin, thus no alarm. Happens with lintier threads. Just wipe it off with your finger or a Q-tip from time to time.