The printhead carriage contains the heads, the ink (in almost all designs) and connections to the print head. The carriage is moved by the carriage belt, carriage motor (for large scale motion) and stepper motor (for the tiny motions which allow one row of bubble jets to consecutively print to form letters and other characters). It rides on a stabilizer bar linked by pulleys attached to the carriage motor.
Pickup rollers in the paper tray or paper feeder work against coarse cork or rubber separator pads to pick just one sheet at a time, and are turned by a printer stepper motor. Clean those rollers and pads with mild soap and warm water; alcohol and solvents can dry out rubber and cork.
Paper feed sensors watch for jams and report to the printer control circuits. Those control circuits connect to the interface circuits and the printer's buffer to process data, and the power circuits turn wall outlet power into the voltages (typically 12vDC and 5vDC) needed for the motors and logic of the printer.