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if printer is not in warranty, clean the print heads with some alcohol solvent or medical spirit. DO NOT use any water based solvent. You may soak the heads in solvent but not for too long.
If you already tried cleaning the print head / cartridge then there are only two possiblities : 1. The print heads are worned out with usage.2. The cartridge you bought is faulty (less probable)
If the printer is in warranty then you should get it repaired by make for free. If not, you will have to buy new print heads.