If your extruder motor suddenly stops turning, start by checking the SRD (Serial-Resistor-Diagnostic) status. The motor may have overheated or be experiencing electrical issues, such as a blown fuse or loose wiring. Ensure that the motor and power supply connections are secure. Inspect the stepper driver for any fault codes or flashing LEDs indicating an error. Additionally, check the engine for physical blockages or mechanical jams. Perform a quick calibration test or reset the printer to see if that resolves the issue. If the SRD status shows an issue, replace the faulty component.