A friend and I were quilting her quilt when we got a tone and a message that said "Needle sensor failure". I turned the machine off, turned it back on, did the Needle Diagnostic which passed, so we proceeded with a new needle. Very shortly after that, my friend said the thread broke but it looked more like the bobbin was out to me. When I tried to get the bobbin case out of the casing it would not slide out. I looked up and the needle had come OUT of its needle bar and I could not tell if the thumbscrew was loose because the needle was already out, so of course was loose.. So the needle had dropped into the bobbin casing. I was able to get the needle out from above and indeed the bobbin was empty. I replaced the bobbin with a full one, replaced the needle again and did the diagnostics again and it passed. We proceeded but we noticed it was making a funny 'light clicking sort of noise and we stopped.
I pulled the throat plate off and could see nothing wrong. My friend slowly turned the handwheel ...the bobbin with its case case was out so I could see what was happening inside. There is point at which the needle is being barely touched but definitely touched, by a piece of the bobbin casing (shuttle??) as it moves around. You can hear and slightly feel the click as the needle is hit. I don't know the names of bobbin casing/shuttle parts so can't explain any better.
What should I do?