Ink has run out ??? it no longer prints... TSP100 How do we change the ink roller/cartridge or whatever it requires?

I see so many problems people have with printers, and it's understandable. Printers work great, as long as nothing breaks or jams or the ink cartridges are maintained. To keep ink cartridges from drying up, you should print at least a page or two on a weekly or at least monthly basis. This keeps the ink from drying up on the print ports that supply the ink. Also, there is a heater on HP, Canon, and other printers that is inside the print cartridge. When the ink runs low, the heater element can burn up, and refilling it will not help, a new one will have to be purchased. Dust and dirt and particles can cause havok within a printer, causing sensors to stop working, rollers to stop grabbing the paper correctly, and other problems. Take your printer, occasionally, and, carefully holding it upside down, blow it out with compressed air. Be careful about the scan bed, it can easily break if it flips open too far. If you don't elect to hold it upside down, at least blow it out with compressed air as well as you can. This will minimize problems for you, and make your printer function much longer. Try to keep the printer closed up while not in use, to discourage dust and other things from falling into it. Too much debris, or especially liquid spills can render the printer useless and, at a minimum, expensive to repair. Anything that can jam the rollers, can strip a plastic gear in the roller assembly, and this requires service, and replacement of the gear. Since HP will only send parts to Authorized Dealers (as with other companies), that requires you to have HP fix it, unless you can find a 3rd party repair service.
To conclude, keep the printer clean and free of debris. Print occasionally, to keep the ink from drying up. When not in use, close the printer up, and you can also use printer covers, which used to be supplied years ago, but were discontinued (probably to aid in resales). You can sometimes find them still at certain stores, and used computer shops. Good luck, hope these tips help!