How to get good nozzle check?

When doing nozzle check, color stripes are supposed to be full, like Figure 1.

Figure 1

But sometimes, they look not so good. there are some gaps like Figure 2.

Figure 2

Because that the printer head is clogged, so to clean the head is needed now. Please do followings step by step

1. Let the working table back by pressing Back button. and then make automatic head cleaning one or two times first by F12 from the rip software and try again.

2. If there are still gaps after step 1, Manual head cleaning is needed.

This link to see how to manual cleaning the brotherjet br1900 printhead.