My printer produces coarse output/has banding.

The printhead is likely out of alignment. Running an alignment of the Printhead from the GARO Status Monitor may fix the problem. If the banding occurs when printing from the Cassette and is confined to the last 1.25 inches of the trailing edge of the paper, see below.

There is subtle banding in the last 1.25 inches of paper on cut sheets when fed from the Cassette.

There have been multiple reports of banding in the last 1.25 inches of paper on sheets fed from the Cassette. If the print has a trailing margin of at least 1.25 inches, none of the print will be in the "banding zone" which starts at 1.25 inches from the trailing edge of the paper and ends about 0.6 inches from the trailing edge of the paper.

There is a Banding Test File and exact instructions for reproducing the banding referenced in this forum thread. Some posters have done their own testing and found NO banding when printing as described above. However, when they used the Banding Test File all most have seen some level of banding on close inspection in the trailing 1.25 inches of paper. Banding is generally visually apparent in scenes with soft transitions in the highlights with little detail present to obscure the problem (e.g., monochrome landscape with clouds in sky). Banding has been seen on both resin coated papers and matte papers, and on Canon and non-Canon papers. The level of banding observed appears to vary significantly between different units.

Problem Resolution: Several posters to the Wiki have been studying this problem and looking for solutions. Jim H WY posted the solution that solved his nasty banding problem. The fix was tested by John Hollenberg, who also found that banding was completely eliminated for him. Jim's procedure follows:
  1. Install Firmware 1.23 or later (firmware 1.25 is best)
  2. On the printer LCD menu choose: Adjust Printer -> Manual Band Adj -> Adj Far Ed Feed and set to "Yes"
  3. You can use letter size paper in the Cassette. Printer will print a sheet (assuming you have paper in the Cassette and have the Cassette selected)
  4. Examine the rows C1 and C2 with a loupe and find the column in each row that shows no banding. If you can't choose between two adjacent columns, use a number between them.
  5. Enter the number determined above for C1 and C2 by using the right and left arrow keys and choosing OK.

You need to make this adjustment for every media type you'll be using, and you may need to make it again if you switch to a significantly different paper while still using the same media type. The printer saves these parameters separately for each media type (confirmed by Canon engineer). Thus is you perform the adjustment with Photo Paper Plus media type and then print with Photo Paper Plus Semi-Gloss media type (presumably on a different paper), you will still see the banding (unless you have previously done an adjustment for Photo Paper Plus Semi-Gloss). You can record these values for each paper type and if you have to re-enter them, just print the pattern on a blank sheet 20 lb. bond paper so you can get to the part where you enter the values for C1 and C2. See also the FAQ topic on Firmware Adjustments.

Per Canon Tech Support, both the Automatic banding adjustment and the manual banding adjustment work per media type. The last one (either automatic or manual) performed over-writes the previous setting for that media type. It isn't known how different the values may be for different media types or different papers and the same media types. John Hollenberg found that values for both C1 and C2 of 28 eliminated banding for both Epson Premium Luster and Lexjet 10 mil Gloss (which were printed with different media types, thus separate calibrations were done for each). For additional information, see this forum thread.

Note the coarsening of the dots in this band: