I've had this problem for some time now which normally pulling it out and re-inserting it a few times will remedy the situation. But a few weeks ago I had to reinsert the cartridge about 25 times before it finally noticed it was in there. Replaced two in the last day and didn't have too much problem. I think the black was noticed the first time. The yellow took a couple of tries. Can't remember the one that gave me a hard time but I think it was magenta. There are new OEM inks. Just wondering if the connector needs cleaned (I'm guessing) and what is the best/safest way to do it.