I agree. This board has been such a help to me so many times. It rocks!!

I do not drop my dog feeds but I do use the supreme slider, gene bobbin and the blue bobbin case, I find changing the needle to a quilting needle helps alot when FMQ'ing. Good luck hang in there. Oh...and when I used June taylor spray my thread would break alot...I switched to 505 spray and now it works really well. Oh and also make sure you pull the bottom thread up to the top of the quilt.

I have a 6600 and fmq a lot. I have had to change my tension to between 5-6, if the problem is with the back of the quilt. Also I have learned to not turn quit so fast and the stitches stay more even on the back.
But I am going to try and raise the feed dog up. I have heard a lot of quilters do this and the stitches are better.

Since it does seem to work in one spot, I would wonder if that is at the beginning of your sewing/quilting session. If it does sew better at the beginning, finish that section, then when you want to move to another section turn your machine off and leave the room for a few moments to rest, stretch, de-stress, and have a drink of water! Then when you are a bit more relaxed, remove and re-thread the top and remove and reinsert your bobbin, as if starting fresh again. Some machines are very fussy and need some TLC. I have also found that using the same thread top and bottom is crucial (different colors are okay)! My mom has a Janome Quilter's Companion that seems to be a little needy, as well!

Little Roo....I am dealing with the exact same thing right now with my 6600. Literally, I've spent the last 3 nights fudging with this quilt. I've switched threads, switched needles,switched needle sizes, changed tension, changed pressure, used the blue bobbin casing, and cleaned/ recleaned the machine, and rethreaded it a million times. I am very experienced at FMQ so I know what I'm doing with speed, etc..
I had a basic little 4623 janome with a small throat and got beautiful FMQ stitches, no messing around. This machine is so tempermental. I love the larger harp but there are ( many ) times I've regretted the money I spent on it.I'm gonna try to raise my feed dogs too.

I don't have any experiences with Janome, but I would take it back to the dealer. You shouldn't have to go through this nosebleed while FM. You're doing everything by the book, good thread, new needle, etc.

I have the Horizon and do leave the feed dogs up when fmq-ing with stitch length set at zero. You may want to watch Leah Day's tutes. She uses the Horizon and is my idol!

Change your bobbin completely.I had this problem and never before or since.The bobbin was not true to shape.Worth a try if you've explored everything else.

Just love this group for good support.

I haven't had many problems with FMQ but I do notice when I am doing a pattern stitch and get going too fast it does tend to birdnest on the back. Anyone have this problem. Love this board. Have learned so much. Thanks in advance.