CONGRATS! You issue reminded me of the Singer Sewing Machine my mother bought back in 1965. It NEVER worked right - would break the threads like yours. Sometimes the repairman would have the machine for months at a time. The repairman would say we pulled the fabric thru -- don't do that. Then he said we pushed the fabric thru -- don't do that. He came up with all kinds of excuses. Finally, he left town and another repairman came in --- looked into for 2 seconds and said there was a chip in a piece of metal inside....THAT was shredding the thread!!!!!