You are not a bother to us, this is why we are here......
I have numerous Janome machines. the 6600 is an incredible machine!
Change your needle to a 90/14 topstitch needle. It sound like your machine thread is not "locking up" with the bobbin thread, thus the top thread will just come out. Also, are you using your accufeed foot? It is like a walking foot, only it fits directly on your needle shaft? Rethread your machine, change the needle to the 90/14 topstitch. I hope this works. It is sooooooo frustrating to have to take out stitches, we have all done that more than ten times....you are on the right track for getting it done. One other question, are you pulling on the quilt this can cause skipped stitches or not locking with the bobbin thread. Since you were able to pull the thread string, it sounds like the needle is not going down far enough to catch the bobbin thread. Make sure your bobbin thread is coming off the bobbin in the right direction. Also, there maybe suggestions in your manual on thread nesting in the bobbin. BTW the 90/14 topstitch needle makes a larger needle hole so the needle and thread can get down to the bobbin area. let us know how you are doing.