I read an article in a quilt magazine a long time ago that said leaving feed dogs up when free motion will eventually damage the machine. I don't remember the reason it would. I guess it was proven wrong as I have not heard any machine repair say not to. If they even know the feed dogs are left up if you free motion. I asked the repairman that fixed my Brother and he just said the feeddogs are made to drop for a reason. But he didn't have a clue.