On some toner cartridges you can even tape a piece of paper over the sensor window on the side, that is used to determine fill state with an optical sensor, to

On some toner cartridges you can even tape a piece of paper over the sensor window on the side, that is used to determine fill state with an optical sensor, to get another ~500 pages. Example pictures: https://geekanddad.wordpress.com/2014/03/02/ https://geekanddad.wordpress.com/2014/03/02/