Innov-is NQ3500D FAQs & Troubleshooting Innov-is NQ3500D Not your product? Sort by Updated Date Popularity 33 Results 31. 29/07/2016 "Check and rethread the upper thread." message appears on the LCD. What does it mean? 32. 29/07/2016 "This pattern cannot be used." message appears on the LCD. What does it mean? 33. 12/11/2015 "Preventive maintenance is recommended" appears on the LCD. Error messages FAQs & Troubleshooting