I just got my FW this month ...so sorry you are having trouble.. It will probably be something so unnoticeable...check for things like small threads under the tension bar on the bobbin.. or upper disks.. I once had a needle holder fall off and replaced it up sidedown..for years I fought that sewing machine to make it work..one day I looked at the lines on it, they didn't line up. turned it over and it worked ...no more problem Hope you find the problem!!