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[Jim Hancock]

You have an electronic issue on the black channel (not the black head itself), this is not a printhead issue. It could be the carriage board, but more likely the mainboard. Did you verify the ribbon cable I pointed to is in straight? As always, with the printer unplugged for 15 minutes, verify both of those big ribbons are OK by pulling them out of their connectors, check the traces and carefully plug them back in. You can also put the head cables back in their proper locations, as we have verified this is a black channel signal issue. Then do another nozzle test and post the results.

 

[Jim Hancock]

So these results are clear to you, what you have done is to drive the K/C head with the M/Y signals and the M/Y head with the K/C signals. Since the problem moved, it's a black channel signal issue, not an issue with the head itself.

 

[Lightbulb88]

Gotcha

 

[Lightbulb88]

After power down and removing of the large ribbons, and putting the printhead ribbons back into place. The machine did a cleaning and afterwards I did a test print. Nothing printed, all colors gone.