I think we eliminated thread as a possible cause by changing out. Also, she has used this brand of thread without difficulty for a long time.
I do think it's worthwhile to look for that bit of thread that may be in the bobbin case somewhere....
Also, the needle threader no longer aligns properly.
As a side note - she was able to sew without difficulty all day yesterday with the same thread/bobbin combo....
Very puzzling...
I told her the problem was the machine and she should buy an Elna....lol...