Excellent news, I'm glad to hear you were able to get the M channel printing again! Did it return after changing the damper, or just after some manual cleaning?
Regular manual cleaning of the printer's capping station, flushing box and wiper blade are important to keeping the print head clean and in good working condition, to get the best quality output and longest life from your printer. If you're not already familiar, you can find our manual cleaning procedures here: http://www.inkjetmall.com/tech/content.php?133-Printer-Cleaning-and-Preventative-Maintenance
You don't want to touch anything that comes into contact with the print head with your bare hands, because oils on your skin can cause problems with the print head. It's best to wear rubber gloves when handling the print head or wiper blade. The capping station, flushing box, wiper blade and print head (and other internal parts) can be cleaned with PiezoFlush. I believe we have replacement wiper blades for your printer model, though they are not currently listed on our website, so you will need to call or email to order that part. You can email our sales manager (Wells) at email@example.com.
If you have PiezoFlush carts in all eight channels of your printer, then the best way to flush your printer is by doing an Initial Fill Cycle (which you can find directions for here: http://www.inkjetmall.com/tech/content.php?151-Initial-Fill-Procedures-for-Epson-Pro-Model-Printers). If PiezoFlush has made it's way to the print head of 7 channels, but not in the magenta line, then you may only need to do 1-2 Power Clean Cycles to move PF the rest of the way thru the M channel.
It's best to replace all eight dampers at the same time (the dampers and other parts should be replaced every 1-3 years, depending on use, and clean your printer regularly, as well as regularly agitate the ink cartridges to maintain in-suspension pigment for full/accurate density, and consistent output).
I have only used the Adjustment Program when changing a print head, and have never used it when replacing other parts. It's important to carefully inspect dampers (and any part, for that matter) to make sure there are no punctures in the thin plastic membrane, or other damage, before installing into your printer. I have certainly had new parts arrive damaged, so it's always best to inspect before installing to avoid headaches and frustration of dealing with a non-working part.
I hope this helps, please let me know if you have further questions or there's anything else I can help you with.
Best regards~ Dana