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The right thing to do in such a case, is to first determine whether it is the cartridge, or the printer, which is the problem.
There is no 'recognize switch', so I advise against further disassembly of the printer in trying to find it. Electronic circuitry in the printer and in the cartridge are supposed to interface with each other, and signal properly to each other in recognition (more or less, as a loose description.) That recognition is not taking place, and the fault could be on either side of the interfacing of cartridge and printer.
Try a different cartridge, following instructions scrupulously as to detail. If that too remains 'unrecognized', then your printer is defective somehow (and, yes, cleaning of the contacts might help if the contacts are dirtied, e.g. if you touched them on the cartridge, the cartridge may be ruined...)
Let me know how it goes, and what you think, and what else you need to know. (As to repairability, the printer's age is a factor.)