Remove the bottom panel. Remove the wires from the turntable motor and check for 120VAC to the motor while the microwave is "on".
If there is proper voltage then the motor has to be replaced.
If there is no 120VAC then the problem is a bad control board.
- The part number for the turntable motor is AP2024962
- The part number for the control board is AP2026271
Here are the break down diagrams for the GE microwave Model JVM1410BC001