A few years back I ran into a problem with a Xerox 7700 laser printer. The print quality had been OK, but suddenly the printer reported that a toner cartridge had to be changed and refused to print anymore. After checking up on prices it seemed like we needed to spend 200 EUR to buy a new cartridge.
I googled around a bit and found out interesting piece of information. It seemed like the toner cartridges had some kind of memory units regarding print counts. Once the counter reaches zero, the cartridge stops printing. At this point I decided to hack the cartridge back to a working state.
1. First I removed the toner cartridge from the printer.