I recently had a warranty replacement on a 4900 for two unfixable clogs (extra thanks for the extended warranty suggestion, BTW). FYI, I was running a combination of Epson and Conecolor inks, slowly replacing the Epson carts as they ran out. When I received the new machine, I installed the starter cartridges and stored the ConeColor carts until needed. Yesterday the starter LK cart needed replacement and I put in the ConeColor cart. The cart was not recognized and the X in red circle flashed. The odd thing is that all 4 of the remaining starter carts on that side also became unrecognized, so all 5 gave me the flashing error. Re-inserting the original cart made all recognized again.
Today I pulled out the 4 remaining starter carts and replaced them all with the ConeColor carts. Then the LK was recognized and all seemed to work fine. Twice, though, the printer told me the LK cart needed replacing. I pulled the cartridge out and re-inserted it and it was recognized as full. Right now the printer is running okay, but I'm concerned that it could quit on me again. Could it be a bad chip on the cartridge?