XL-3500/ 3510/3520 FAQs & Troubleshooting XL-3500/ 3510/3520 Not your product? Sort by Updated Date Popularity 5 Results 1. 03/07/2015 How do I install the bobbin wound with thread? 2. 03/07/2015 How do I wind the bobbin? 3. 17/01/2011 How do I pick up the lower bobbin thread? 4. 07/04/2009 How do I correctly install a bobbin? 5. 04/03/2009 How do I wind the bobbin? Getting Ready FAQs & Troubleshooting