AMT Datasouth Codewriter 4500 Series - Manual (Page 64)

Troubleshooting Guide
54
Missing Dots in Label
See Printhead Cleaning in the Maintenance section to see if this
procedure will solve the problem.
Thermal Printheads reaching the end of their operational life will exhibit this
symptom. Although you may continue printing without damaging the printer,
make arrangements to obtain a new printhead.