Originally Posted by
ArchaicArcane
The 401A that I was rehabbing this weekend had this problem. Sometimes it would break the thread outright, sometimes it would just shred it and leave part intact. I changed out the throat plate and the problem disappeared. Looking closer at the plate, someone had hit it hard enough that it looked like it had been drilled. The needle had to have been buried up to the shaft!
You can use some emery string type stuff - sew-classic sells it - and polish up the hole.