CV3440 FAQs & Troubleshooting CV3440 Not your product? Sort by Updated Date Popularity 5 Results 1. 02/22/2018 The thread tension is incorrect. 2. 02/22/2018 Fabric is puckered 3. 02/05/2018 Stitches are not uniform 4. 02/01/2018 The fabric becomes wavy after sewing 5. 02/01/2018 Stitches on back side are not made. Sewing (Cover stitch machine) FAQs & Troubleshooting