I deleted your duplicate post to keep one thread.
What channel was blocked when you started this cleaning?
When you flushed the print head using our print head cleaning kit, did you have a folded paper under the head to absorb the PiezoFlush?
Did you flush just the one channel you were having trouble with, or all 8 channels?
When you were done flushing the head, was there excess PiezoFlush in the cartridge chamber, around the points that pierce the bottom of the carts?
I see you purchased the first set of R2880 refill carts along with ink in Aug 2011, then more ConeColor ink in June 2012, and a second set of refill carts in Sept 2012 with the chip resetter. The print head cleaning kit and PiezoFlush were purchased last month. The new and old model carts can be used together, and the chips are the same on both models (I have use them together many times without any problem). Do you still have the first set of carts, or have you already discarded them? When you manually reset the cartridge chips, does the resetter light flash red a few times, then turn solid red or solid green? Have you tried removing all the carts, then turned the printer off for a few minutes, turned back on (all ink out lights will be on), pushed the ink change button, then reinstalled carts (making sure they snap snugly into place)?
Please keep me posted, and let me know if you have questions or there's anything else I can help you with.
Best regards~ Dana