Glad it was a FREE fix, and you figured it out!!!! We've all done this kind of thing....mine is to put the bobbin in backwards even though I've been using this machine for almost 30 years!
Oh, I empathize with you! I was feeling the dread you must have felt as you tried all the solutions, and then I felt the sense of relief when you realized what was wrong. Good writing, Good result!
You didn't think that you were the first one to do that did you? LOL At least you realized what it was before you took it in for repairs. I wish I could say the same.