Hmm. All I can say is that maybe she needs to stay away from those brands. I know that some machines are picky about what threads they will sew well with. Some people will swear by a brand and someone else will think that brand is garbage because their machine "doesn't like it". Especially fussy seems to be blues, blacks, and other dark colors. I understand that some companies will take lighter colored threads that somehow were messed up in the dying process and re-dye them in a darker color (frequently black). This re-dying causes additional stress to the thread, making it break easier. Wish I had a better solution than that, but it's all I have. =[
that is for sure!
As best as I can understand it is a specific thread problem that is why she stated the two specific brands.
I don't have that particular machine, but I know that tension problems can be caused by a whole bunch of different problems. What type of tension problem is it? Is there lint in the thread race or around the bobbin? Has a needle broken lately? Is the tension just off when using those particular threads and it is fine with other thread? I guess I would need a bit more information before I could offer even an educated guess. Good luck with solving the problem!
Yes, good luck!