I'm not advanced at free motion, but when using a buttonholer or a monogram attachment (for zigzag) the cover plate is an improvement. My 99 and 66 can't lower the feed dogs and the cover plate results in neater stitching. When I free motion on my 201 I have struggled quite a bit with tension, but I can't notice any difference feed dogs up or down? I read this advice too, but when I tried it out it didn't seem to matter. What made a difference was working with bobbin tension and top tensioner, lots of disassebly, reassebly and cleaning; and additional practise. Maybe quilting cotton doesn't catch much when it runs over the feed dogs?
Last edited by Mickey2; 01-31-2016 at 08:16 AM.