Yes, our Janome's can be thread divas. I have a Janome 6600 and now that I have it fixed again, I wouldn't trade it for anything...might have to get a new one some day soon LOL. Anyway, as to your thread question: MacThayer had several good points, however, I would go out and purchase ONE spool of Aurafil thread (50wt) and try it out, or try Mettler thread. Buy just one, give it a thorough run and see if the bird's nests are gone. Now, as much as I LOVE my 6600, she is a thread diva. She will chew up and spit out Gutterman and Coats and Clarks, but, sings like a canary when using Mettler or Aurafil. As much as I love these machines, if the bird's nests still occur then I might try a bobbin washer. Janome had isssues with their bobbins in the 6500 & 6600s and were supposed to rectify that problem with the 7700. Anyway, yes they are finicky machines, but, I still wouldn't trade her. I have a brand new Husquvarna Sapphire 875 that my DH bought me last summer, and I still prefer my Janome. Good luck and let us know how you make out.