The only way I can see it would damage the machine is if the feed dogs are impeded from moving. As long as they can still move back and forth, there shouldn't be any damage and if your stitch length is set to 0, they're not going to move much anyway so not much worry. I was always told that if you couldn't drop your feed dogs and you had trouble with catching the fabric on them, just cover them up as Annababy said.