I am FMQ'ing on my PQ Brother 1500 S these days and I use nothing but Bottom Line in the bobbin, which is vertical on this machine. Most usually, I need to adjust the top tension lower to get the stitches right. I use the same thing on my Kenmore/Janome 19606 horizontal bobbin, (no special case for this), and the same thing applies, have to lower the tension somewhat on top. Top thread, I use whatever, many different brands and varieties in topstitch needles. I am so grateful that this machine has no gourmet taste when it comes to thread. I love each of these machines for FMQ, depending on the size. The Brother has a much larger harp area, which is why I bought it. It is a straight stitch machine only.

I took a class once from a Superior rep and she said that Bottom Line is a poly thread and very slippery besides being a smaller diameter. She would use a larger diameter cotton thread in the top like King Tut. She also used a size 12 needle. I tried Bottom Line on both top and bottom and had a horrible mess....Janome 6500. Switched the top thread to Aurifil which is a 50 weight cotton and everything was fine. It's worth the effort to get the tension right just to have the larger throat space in my mind.

I have the Janome 6600P and have been FMQ on it and have had no problems with the machine - which I love (my technique still needs lots of improvement!). I have the blue dot bobbin case and mostly use Guterman threads and a 14 needle size - my machine seems to do well. The only time I have eyelashing and birds nests is when I forget to put the pressure foot down and I notice that almost immediately. Hopefully you can get yours running smoothly - I know that is frustrating!

The first thing I would do is to change needles. Bottom Line is a very fine thread and you are using a huge needle. Try a 60 or 70 needle and see if that helps. Don't get discouraged. If a high quality machine is giving you fits, then there is probably a good reason: user error! On a scrap fabric quilt sandwich experiment with changing one thing at a time. Good luck...you will figure it out.
BTW, I use Bottom Line in the bobbin AND on top all the time in my Bernina with no problems.

I bet it will, or at least help a ton. As far as I know, there isn't a self adjusting bobbin case out there. To say that one setting will work for all types and weights of thread is not just misleading, it does a horrible disservice to the machine, because it will get a bad reputation for being a stinker when it's really a victim of the marketing.

Can you post a photo of the bobbin case? There may be another way. When I can't use the drop test, I use a method using a 1 oz weight. In my case, that means a baggie full of Kamut berries.

I talk about it here: http://www.archaicarcane.com/bobbin-...obbin-tension/
and there's a photo here: http://www.archaicarcane.com/lessons...ing-the-twins/

I'd take my complaints to the place where I bought the new machine and see if they can't help you get some better results. Hopefully they have customer support.

Tammi, the bobbins for the Janome look like this.
http://www.fabric.com/ProductDetail....6-d06a6b1abddf

And the bobbin case like this.
http://www.amazon.com/Janome-Bobbin-.../dp/B0054E3YU0

K, I think the 1oz weight method should work.

Tantrums can be a very good way to get the point across. No worries, we've all been there for some reason or another. I took a set of machine quilting classes and one of the exercises we did may help you too. Make a small sandwich of plain muslin and mark lines at 1" intervals across the sandwich. Mark each line in succession starting with 1 and go up to the highest number of your machine's tension setting.

Then set up your machine for FMQ. (I agree with the others that the Bottom Line is more for the bobbin than the top and if you use 50/3 weight in the top, try a size 80 topstitch needle.)
Then turn your top tension to 1 and sew within the first area not worrying about anything other than laying down some FMQ.
Now turn your tension to 2 and sew in the second area. Then turn the tension to 3 and sew in the third area. Until all tension settings have been tried.

Now inspect your piece front and back and see where your machine has the best combination. That is the tension setting with THAT needle size and THAT thread combination that will/should work on your real sandwich as well.

Yes, it is a little tedious but it should help you determine what's up with your machine.

I'm also not sure about the Janome and if the stitch length has to be set to 0 or not.

Don't give up. I know that Janome fans are very loyal and there are a lot of them. They can't all be wrong. Give it a try.

Just wantd to pop back in & thank you all for your comments, suggestions & sympathy. I've spent the past hour adjusting the bobbin tension. MadQuilter, I kind of did what you suggested. I wrote on my muslin sandwich just what top tension I was using. So far, nothing is really helping. At first I was actually getting the eyelashes on top. That was a switch! Anyway, I think I'll start fresh tomorrow. Right now I have a terrible headache & feel like I'm starting to hate this machine & I really, really don't want to feel that way. But dang it, I got the machine because I wanted to sew, not be a mechanic! Again, thanks for listening to my childish outburst. I think my headache is better.