I think the problems must have been resolved as there hasen't been any follow up. I have a Janome 550e and I usually fix these type of nuisance's, 1 Re thread from #1 through 2 change needle 3 change bobbin.this is usually the main contender .if it happen again x 2, I throw out the bobbin there is a problem with the wound tension or the spool is damaged. 4 clean out the bobbin case fluff or bit of thread can cause havoc. 5 If fraying continues I toss the spool of thread. 6 check bobbin case that its not damaged from needle strike. I think "Kiddynurse" main problem is the bobbin,if they are using the 500e bobbin winder it's the worst bobbin winder Janome has ever put on a machine.They should try brought bobbins to start with and then bobbins wound on a machine that has a separate winder motor..I do wind my bobbins but do it on the 6700P far superior in tension to 550e winder just absolute junk..As far to adjust tension on 500e you cant it automatic.