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. 07/04/2008 How do I wind the bobbin? 5. 06/11/2007 How do I correctly install a bobbin? More FAQs (English only) Getting Ready FAQs & Troubleshooting