In a large bowl, combine egg, soup, stuffing mix, and salt. Add ground beef; mix well. Shape into 1-inch meatballs. Place meatballs in a baking pan. Bake in 350 degree oven for 15-18 minutes or till done. Drain meatballs and transfer to crockpot. In a bowl, combine ketchup, tomato sauce, water, brown sugar, Worcestershire sauce, and vinegar. Pour over meatballs and stir gently to coat. Cover; cook on High setting for 2-3 hours. Serve immediately or keep warm on low setting up to 2 hours. Serve with toothpicks.