Stratasys J850 Manual page 76

8. When the following screen appears, tape a sheet of pink paper to the
surface left of the build tray, close the cover and click
The printer prints a frame on the build tray and then prints the Pattern
Test on the pink paper.
9. When the Pattern Test is printed, carefully inspect it, using the Missing
Nozzles Ruler to see if there are missing lines.
Each missing line represents a faulty nozzle in the print head.
.