On Leah Day's website ( leahday.com ) she FMQs with the feed dogs up and the stitch length set to 0. She has a video on this, if I remember correctly. I have tried it on my 15-91 (yes, I know I can drop the feed dogs on a 15-91) and it worked fine, but it has a verticle bobbin. You could try that and see if it works on the 66.