Microwave shows E9 and will not start; often associated with turntable or motor issues.

Safety first: Unplug the microwave before accessing the bottom panel or motor.

• Check for mechanical jams: Remove the glass tray and roller ring. Clean any spilled food or debris from the cavity floor. Inspect the plastic coupler that drives the tray for cracks or obstructions.
• Test without tray: Run a short cook cycle with only a cup of water and no glass tray. Look through the window to see if the coupler turns. If it does not move, the motor may be faulty.
• Access the turntable motor: On many Oster countertop models, the motor is accessible from the bottom. Remove the bottom cover screws, then disconnect the motor wires. Test the motor for continuity with a multimeter; an open reading indicates a bad motor.
• Replace if needed: Install a new Oster-compatible turntable motor and reassemble. Ensure the coupler is properly seated on the motor shaft.