So I'm having a new problem with my HP L25500. It gave me a faulty print head error right before Christmas and it's been an oversized paper weight ever since. I went ahead and replaced #4 like it said. I know, replace in pairs, but for some reason I only had one in stock. So I replaced #4 and it stopped midway though the alignment. It was printing terrible so I assumed that was the cause. It did multiple head cleanings, etc. and got most of the nozzles firing. I went to do a test print and it looked great. Printed a 2'x3' banner and it came out perfect. Sent the next file and got 3-4" before I lost black. Back to cleaning. I pulled #4 and blotted the head. there was black and yellow in it. Put it back in and still get crappy - no black ink. Told me faulty y/k head again. It wanted me to replace #4 again, so I ordered and replaced again. Did the exact same thing. Perfect yellow out of #4 and no black, but #3 fires both colors. I don't think that my original #4 head was even bad. It seems the flat cable had come out of it's guide on the one side. I just popped it back in and lined it back up. Reinstalled the head and it took it just fine. It automatically started the alignment and no black. It will go in spurts. One cleaning and I get maybe 1/3 of the nozzles to fire and another one and I lose them all. Do another cleaning and a few come back. Pull the head, blot and there's ink. Same issue with 2 print heads. Any ideas why 2 different heads won't print black?