There are two main reasons:
A. The reasons of clogging printhead
B. The reasons of aging printhead
The solutions:
A. Firstly print on the clean testing stripe, when it shows color piece in the printhead nozzle, it means the printhead nozzle has been damaged, we cannot continue to use it and we need to replace a new printhead.
B. When it shows break line in the testing stripe, it means this printhead nozzle is clogging, we may continue to use by cleaning it.
Printhead cleaning method:
We can clean the printhead by using the ink absorption and it can be cleaned manually. First use warm water to soak it for a few minutes, use soft paper without scraps or a piece of specific cloth dig in the printhead or dry in the air. We mustn’t wipe the printhead at this moment and we can do print test after drying.