Laser toner cartridges operate with high voltage and an extremely fine toner powder that is placed onto the print paper via a magnetic developer roller, a laser beam process and an electro photographic light sensitive drum.

The electrically charged characters, formed in toner, are placed onto the print paper that is also electrically charged to hold them in place. The paper is then passed through a relatively high temperature fuser roller that melts the characters and permanently fixes them onto the paper.

The drums are susceptible to damage from exposure to light, especially bright sunlight. Drum shutters reasonably protect some types, while others have a shutter and a slot where light can readily fall on a strip of drum surface.

Missing words, missing lines or faint printout are the indications of empty toner. Get your toner refilled or replaced immediately after it gets empty. Do not fire further print commands, because of which all the internal parts get damaged.
The laser toners which are chip based generally indicate if your laser toner gets empty.

You can get your empty cartridge refilled for 3 to 4 times, but before filling one should clean or remove all the previous toner powder from all the internal as well as external part and then fill the new and best quality of toner powder. After refilling for 3 to 4 times, you can remanufacture the same cartridge. Each printer has different type of functions and needs, and accordingly, toner powder is developed to suit a particular printer. One cannot use the same toner powder for all types of cartridges. It reduces the life of cartridge.

Do not leave the cartridge in motor vehicles for any length of time, as even on a cool day the temperature can exceed safe levels. Doing so may distort the plastic in the cartridge.