While I am still having problems going through the matrix of diagnostic tests and still get "failure" messages on
some of them, I decided to see what happens if I did as much as possible to calibrate the heads, color, etc through the service utilities menus. Here is what I found:
Despite a test error that said the ESP (color sensor) could not be turned on and off, I was able to clean the heads to remove banding. I was able to print and use the head alignment pattern, the color calibration chart, and the APS large target for paper profiling. There were marks on the forward edge of the paper for the first inch or so, that looked like dragging of the edge of the carriage across the paper, leaving horizontal white lines that resemble those from clogged print nozzles. I can't tell if they are from the carriage edge or from something else. However, when I made a test print and left an extra inch in the margin on the leading edge of the paper, the print came out fine. The lines, which on closer examination included a few horizontal lines of faint black ink, look again as if something is pressing down on the paper. But the print itself was perfect. I used one of these test prints that includes 2 photos, a Macbeth color checker, a sharpness scale, grayscale steps and a color strip.
I compared the print made with on old profile to the print made with the new profile, and the differences ere very minor but the new profile was actually better.
I'm not sure what is causing the horizontal lines across the leading edge of the paper, but as of now I can work around that when I print. I assume that the color sensor is working fine despite the failure I mentioned above during diagnostic tests, and alignment is otherwise accurate, since my calibration print and profiling target appear sharp and accurate (except, of course, for the few white lines across the first inch of paper).
I know stuff is still in need of fixing. I may even have caused the problem with the lines at one point when I tried rewinding the paper while the printer was off and got it to move a couple of inches before I realized I should have lifted the media lever. That was also late at night and the brain was not in gear.