Normally when the sensor doesn't work, your machine will stop giving you false thread breaks " Red Light". However not necessarily mean the thread break sensor is not working it may be dirty and it can be fix by cleaning it. here is a link of another video we have showing how you can test your thread break sensor. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-otZ9aT6lqVY.html
