I have two 3880 printers; one for monochrome with K7 piezography and one for color using OEM cartridges. I filled a set of cartridges with PiezoFlush (PF) to flush the monochrome printer. When I inserted them, I got a “Maintenance Cart error.” After some research, I saw that this is a cartridge error, not an MC error. To confirm, I put the Epson color cartridges in the monochrome printer and everything was fine, no errors. I put the Epson cartridges back in the color printer and one-by-one swapped the OEM cartridge with the InkJet Mall cartridge containing PF. I found one cartridge LK that was a problem. On examination, I found the little plastic tab at the rear of top board was broken off which didn’t keep the card in contact with the chip underneath. I replaced that top board with another I had. This worked in the color printer, no errors. But when I put it in the monochrome printer, I got the “Maintenance cart error.” I’m not sure where to go from here. Any suggestions?