I got a Janome QC6260 for Christmas and have only been using it for a few weeks, and not very much on top of that.
Yesterday I dropped the feed dogs with the lever on the front to test it and then left it because I didn't have a practice sandwich for trying stitch in the ditch or waves. Tonight I went on to test the walking foot nad see how I get on with quilting on it, and the feed dogs won't come back up. In fact, if you press the pedal it starts hammering the needle down really quickly and will continue for a bit even when you take your foot off. :-(