turbguy,... I think your looking at the wrong thing. For what you are searching for you need to use your 10x mag on the color grid matrix patterns that are in the middle. The photos that you print use virtually no black ink at all so they are not involved. Looking at the black bars on the far left and right will tell you nothing about how your pictures print, They are primarly there to show paper alignment. With your 10x mag, look at each of the Cyan, Photo Cyan, Magenta, Photo Magenta and look at each line. So that you understand what you're looking at, each matrix or Grid pattern is made up of short firings of nozzles. The far left vertical line of the grid is all nozzles firing at one time. This makes the vertical line. With no delay, since the printhead is moving from right to left, the top nozzle (and the 10th, 20th,30, etc.) fires for a duration of about 1/32". This makes all the first set of horizontal lines. Then all nozzles fire once again. Then the 2nd nozzle (and the 11th, 21th, 31, etc.) fires for the next 1/32". Thsi makes the second set of horizontal lines. If you look close with the mag you will see the 2nd segment is stepped down by the distance of one nozzle. The grid pattern is continued until each and every nozzle has fired. So if you look close at the grid with the 10x mag, you can verify that each and every nozzle not only fired, it fired at exactly the right time and it was in place. If you can look at all your color grids and verify each line segment is there and not smeared or off line, you will have proved there is no possible clog in the print nozzles. Once other key thing to look at in the grids is the spacing. The vertical spacing is just the distance of the individual nozzles. The horizontal spacing is controlled by the timing strip in the printer. If there is dirt, dust, ink, or anything else on that timing strip, things will print screwy horizontally.
The Service Test Print can tell you just about everything on how your printer is performing. Every line, color bar, and printed text has a specific reason. For example, the very top horizontal line is a test that the paper feed mechanism can register the paper correctly and get it not only square as it feeds the paper, it also gets the line in the exact starting point. The vertical black lines are a test to prove the paper continues to feed straight and the timing strip can return the printhead to the exact position, time after time, at the correct speed, and that the printhead fire exactly at the right time, and that nothing wander out of correct registration. It is actually a thing of beauty for any Service Engieer to see all these test come out perfect. Then you know you have fixed the printer and it is in great condition.