I met up with a friend last night and during our conversation about antique and vintage machines she mentioned she is having an issue with her Singer Touch and Sew 770. When she sews the top thread is beautiful stitch but the bottom thread is a mess. This is a person who knows her way around machines pretty well. We ran through the first steps pretty quickly- threading, needle, bobbin threading, etc.
I told her I would post to a board I belong to where folks are pretty darn knowledgable to see if we can find the answer.
If you have any suggestions to help the mystery, she would be greatful. She really doesn't want to send the machine to the recycling center. Like most of us, she has multiple machines. :-) Good girl.