I just got this beauty today. No manual was included. I was able to get her threaded and sew a few lines. But there are a couple of knobs I can't figure out. One raises and lowers the feed dogs, although I've never seen a machine with multiple settings for this. The other is right next to the stitch length lever. I have no clue what it does. I've looked at Singer 15 manuals but they don't show this dial. So far I've had no luck locating a Super Deluxe Precision manual. Can anyone help with either a source for a manual or information on the unidentified dial?