Pdf is blank. File is too large.
Reduce it and try again
I had no trouble downloading and viewing the pdf.
Clearly the Magenta cartridge has problems. I would take it out and shake it a few times, reinsert it, and try another nozzle check (without a cleaning). If it still isn't perfect, try a new Magenta cartridge and see if there is any improvement.
I had a similar persistent problem recently on my aging 3800, when two cartridges failed to clean up, even after replacing them with new ones. My next try was to spray a little Windex on a Q-tip and dab the opening where the ink goes from cartridge into the printer. I let it sit there for several minutes and then wiped the area clean (gently) with a paper towel. That worked fine. Apparently some ink had dried up right at that point, clogging the entrance.
I should add that my nozzle check always shows all eight patches in a single row across the narrow end of an 8.5x11" sheet of paper, just like what Dan showed, not at all like Philip's pattern.
Here is a jpg screen capture of the essentials of your pdf: