I have a Janome 315. The feed dogs don't drop on mine, I have to cover them. When I tried to sew with fleece I had to resort to a walking foot. I could not fit two pieces under my machine without one or the other sliding all over the place. It seems the space between the foot and the feed dogs was too narrow. It depends on the thickness of the fleece too. Let us know if you get it figured out!
Melissa