Thanks for all the help from the board we took the machine in to the shop last night and just as stated it wouldn't act up for them but they suggested Alot of the same as you did by using leaders and making sure that the machine was keep clean which by the way it was full of lint already under the bobbin holder. I couldn't believe how much was there for it only being a month old! They also gave us a spool of some other thread to try and I bought 20 of the janome bobbins for safe measure.

Hope things are working o.k. now. The better thread will help with the lint problem.

A good source for Aurifil is Tristan Threads. I get great deals from them on Aurifil.

Thanks, fayzer for the tip!

Ah ha!! The Janome 6600 does not like lint under its bobbin case! If it's been sewn on for a month without cleaning it out that's probably what all of your problems were. Clean under that bobbin case frequently!!!

I too have a Janome 6600. I use quality thread, but it still gets linty very often. Just finished a quilt top for a double bed and had to completely clean my machine 3 times. Lots of lint everywhere, then the thread just jams up and won't sew. My husband thought maybe there are some rough parts in the mechanisms and that is causing the thread to cause so many problems. Sounds good to me. Would never buy a Janome again. It can't hold a candle to my old Pfaff which I still have and use as my "traveling" machine.

forget coats and clark. i put up with one of their verigated colors, otherwise my 6600 hates it

I had trouble, too, with my Janome 6600. The lady at my local LQS who sells Janomes recommended that I only use Janome bobbins because they are slightly different than other plastic bobbins. The difference isn't visible to me but I tried that and haven't had any problems since. It's worth a try.
I use plenty of different threads including some older spools, cheaper threads, etc. No problems.

Another thing I did wrong at first was to insert the bobbin in backwards which probably accounted for it running great at the shop but not at home. The thread should be coming out counter-clockwise when putting the bobbin in and then pulled it to the left and upward. I'm embarassed to admit this since its such a rookie mistake but, hey, we all have to learn!

kudos to you, for being willing to admit it.
Many do it but would never "come out"! :)

As you mentioned not all plastic bobbins are the same.

It's important too to use the Janome bobbins ... for all they cost, it's makes more sense to use the "right" ones and avoid the aggravation created by the wrong ones!