Attached photo shows the backside (bobbin) tension issue of my friend’s Janome 6600 (1 year old). This has become a real challenge because the problem is intermittent. The normal steps to correct a problem of this nature seem to work, but only for a brief period. Cleaning, changing the needle, incorrect thread path, bobbin placement, etc. have been eliminated. The weirdest thing is that, at times, when the machine is powered off and then powered back on, the issue goes away briefly. Her dealer has checked the machine on numerous occasions, removed some lint here & there, changed the needle, etc., but has yet to identify the real problem. Yesterday she sewed on it for about 5 hours (after taking it to the dealer). She turned machine off and went to dinner. An hour and a half later, the stitching in the photo occurred. She said she got mad, turned it off, and went to take a bath. After the ‘bath’ time, all was well again. We’re about to conclude that the problem is electronic and not mechanical since tension adjustment is automatic in the Janome 6600. Anyone had experience with this kind of thing?

i have never had that problem with mine.

i think she needs to try another repair shop. i don't mean to criticize the one she's been using, but they seem to have run out of ideas. a fresh perspective might be helpful.

It kind of looks like the problem I was having for awhile. I discovered the bobbin thread wasn't going thru the little slot area, it was just coming straight off the bobbin.

Makes me wonder if there is a tiny thread hidden somewhere in the tension mechanism. They can be hard to find and create a lot of probelms.

it has to be the top tension some times my thread jumps out of the take up lever. if not that i think electronic may be something to look at

The 6600 has a front drop in bobbin and if the thread isn't in the little bobbin tension slot it will cause loops on the bottom.

This would drive a quilter crazy. Start making a journal and write this timeing and how long it works and keep track of this and the samples of the bad sewing. Then you can take the log of written things to the new shop with the beast!

If the machine isn't over the 1 year mark, they should replace it(if it is a computer problem), if she has taken it to the dealer several times for this issue. If it is over a year old, the shop where it was purchased really should lookafter her. Mine was acting up like that last week, and I ended up having to replace the bobbin case where the bobbin goes in...they said I wore mine out(machine is 6yrs old). She may want to try another shop and hopefully she has all the receipts for these visits. If all else fails, contact Janome direct.