Desktop printers have become more complicated as they declined in price. I tried to work on a few. The mechanism often has a number of rollers fastened between two metal plates. A lot of pulleys, gears, bearings, spacers. Looking inside a printer never gave me hope I could disassemble and reassemble it. Mistakes are easy to make, and these printers are designed for a throw-away market, rather than fixing by you and me.
Torn paper can be removed by approaching from different angles sometimes. Upending the machine, etc.
Ink on rollers needs many rubs with solvent, combined with running paper through. Water often works.