You can get PDF versions of the Dymo LetraTag User's Guide and Quick Reference at Dymo.com, both of which contain troubleshooting sections. Dymo.com also has a frequently asked questions section for the LetraTag.
The Dymo.com User Guide has a full page of troubleshooting items and contact for customer support. The Quick Reference Guide has a much briefer troubleshooting section. Staples.com has 83 customer reviews, some of which mention product shortcomings, although the majority are positive.
Amazon.com has 257 customer reviews of the Dymo LetraTag as of 2015 and a customer questions-and-answers section, which contains 28 questions, such as "the ink is fading. What do I do?" and "Tape is not sticking well... what should I do?"