Just went through this EXACT same saga. They finally replaced the printer. Guess what, SAME PROBLEM. This would lead me to believe it was either an inherent flaw in the 9900 or that something is wrong with my side of things. The reasons I am inclined to believe the former (that it is an inherent issue with the 9900) are as follows:
- Epson techs are consistently unable to print a test print without the banding issue in the dark range. On their paper, with their file, sent from their computer.
- Various paper types and brands have been used, all with the same results.
- Various computers with running Windows and OS X using different driver versions (latest included) have been used all producing the same results.
Solutions I have found (well, workarounds really, they don't solve the underlying issue, just sidestep it):
- Significantly slow down drying time per pass in "Advanced Media Control"
- Significantly lower paper feed adjustment in "Advanced Media Control"
These seem to abate the issue to the point of it being negligible. This, however, is not satisfactory. When shining a light directly on the prints, the subtle flaw is usually still visible. This is unacceptable for archival prints which command such high prices.
Would love to see this fixed, but afraid I will forever be dealing with this issue.