Well I tried tracking down the problem again on my 404. The thread is still jamming up under the needle plate. It Is a single hole needle plate not a wide hole as it would be if the machine zigzagged. it will sew along fine for a bit but if I stop sewing to readjust or something and start again, it will jam underneath and stop sewing. The repairman said he couldn’t find anything wrong with it but I think he sews a few straight seams without stopping and it seems to sew fine. Any suggestions? I would really like to be able to use this machine for piecing. Tried removing the bobbin and case to see if there could be a thread caught under there but see nothing. Can’t see anything from the bottom of the machine either. I think we got taken on this machine,