Ever had a giant bird's nest of thread under your sewing with no idea how it got there?  How about a weird noise coming from the machine with every stitch?  Deborah reviews the top three most common sewing machine errors and how to fix them, based on questions asked by thousands of students over the years.  You can read a truncated transcript of this post here:
https://whip-stitch.com/answers-to-the-three-most-frequent-sewing-machine-questions/