Ok, so when we bought this printer C524, it came with toners and they are just now getting low, however, several months later we purchased a new set for backup. I have now (about a year later) found that the wrong replacements were purchased from Staples. It is too late to return them, so I was wondering if (by a long shot) there might be someone with the opposite problem. The replacement cartridges (that I have) are for a LEXMARK C530DN with following model numbers: Magenta: C5340MX (7,000 page yield) Yellow: C5340YX (7,000 page yield) Cyan: C5240CX (7,000 page yield) [This is the only one that has been taken from the original sealed bag, though still full of toner. These look very similar so I placed it in the printer in place of the old one, but I got an error message about incompatibility and then realized The numbers did not match.] ** So, the ones that I NEED are for a C524 (BUT ALSO WORK ON THESE MODELS 524, 524dn, 524dtn, 524n, 532dn, 532n, 534dn, 534dtn, 534n): Magenta: C5240MH (5,000 page yield) Yellow: C5240YH (5,000 page yield) Cyan: C5240CH (5,000 page yield) ** If there is anyone who would have the second set and need the first, I would gladly meet you wherever and trade straight across or even with some sort of deal-sweetener. Or, If someone would have the ability to transfer the toner (assuming the toner ink is compatible, just not the cartridge) I would give you the others or some other thing to be bartered. But I really hate to waste perfectly good cartridges if there is someone who can use them. Or, If someone has a LEXMARK C530DN, and just needs cartridges, I would consider just selling them so I could get mine refilled. oregon