I have the Janome 8200 (a less expensive cousin of the 8900) and I found what helped was switching to a titanium topstitch needle from Superior for FMQ. I seldom have to mess with the tension dial unless dealing with flannel, in which case I need more room under the needle. Also make sure your bobbin is wound properly and your machine doesn't have any lint built up in the race. Clean out the feed dogs before you lower them for FMQ. THey get linty fast.