A horizontal line may be a result of dust or dirt accumulated on the print head.

Clean the print head as follows:

1. Turn off the printer and disconnect the AC Adapter if it is connected.


2. Open the Battery Compartment Cover on the back of the printer and remove the batteries.


3. Open the Tape Cassette Compartment Cover and remove the tape cassette.


4. Gently wipe the Print Head using a dry cotton swab.
   

   Do not touch the Print Head directly with your bare hands.