HP Z3200 printing problem

I have an HP Z3200 44"PS printer. After starting the printer I get a good print. The second print seems to have the black ink fade out near the end of the print. There is plenty of ink in the black cartridge. I replaced the red/black print head and cleaned all the contacts for all the print heads. Same problem. If I wait several hours with the printer off and then print I get one good print, but the second print has the black fade away. The computer for the system is a Mac with OS 10.5.8. This just started happening a few days ago. Prior to that no problems.
Any thoughts?

 

Update 8-27-16

The problem is more defined now. After printing three prints in a row from a cold start with the printer the first two 18x44 inch prints were perfect while the third print had white banding throughout the print in horizontal lines. The print was overall weak because of the lack of ink in the banding areas. It seems to be a problem with the ink delivery system after two good prints. Because of the first two good prints the ink cartridges, ink lines, and print heads should be good. I suspect a thermal problem somewhere in the circuitry. A corrupted driver came to mind, but why were the first two prints good?
Stan Conrad