A method of controlling toner development during a life of an imaging unit in an image forming device by determining whether an end of life of the imaging unit has been reached and upon a positive determination, performing at least one of incrementally lowering a target toner mass to be measured by a toner patch sensor and incrementally reducing the magnitude of voltage biases applied to at least one of the magnetic roll and the charging roll of the imaging forming device. Performing the acts of incrementally lowering and reducing are repeated until the imaging unit is replaced. The method reduces the risk of damage to the image forming device due to carrier bead development while allowing for printing to occur.