The function of the Foam Washers is to keep dust from getting into the sensors. Over time, the sides of the plastic holders might warp inward and reduce the gap where the foam washer installs, compressing the washers and wearing them out over time. If the foam washers break they don’t necessarily need to be replaced, unless there are other sensor issues.
If there are Thread Breaks Not Being Detected or Not Detecting Bobbin Run Out - Or Giving False Thread Or False Bobbin Breaks, follow the steps in the appropriate article. If the steps in the articles do not resolve the issue, contact Melco Technical Support for in-warranty service, or visit www.shopmelco.com to purchase a replacement Thread Sensor if your machine is out of warranty.
Replacement Steps are detailed in the online Technical Manual and in this video on Facebook and YouTube.