METHODS OF VERIFYING REQUIREMENT FOR REPLACEMENT OF A MAIN UNIT AND OF A COMPONENT OF IMAGE FORMATION APPARATUS AND JUDGING ADVISABILITY OF RECOMMENDATION FOR REPLACEMENT

The technique of the present invention reads information, such as a use start date of a color laser printer, a cartridge detachment date, a total number of cartridges, used, a total consumption of toners, a total number of prints, and temperatures and humidities at an installation location, from a storage element of a toner cartridge, which has been attached to and detached from the color laser printer. When either the temperature or the humidity at the installation location is out of its normal service range, the technique modifies conditional values and determines whether immediate replacement of the main unit or each component of the color laser printer is required. When it is determined that immediate replacement is not required, the technique estimates a replacement timing of the main unit or the component, based on the above pieces of information.