Hi Mark,
Remove the turntable tray and the ring. Turn over the oven on its back. Cut 6 joints of the bottom plate using diagonal pliers. Separate the motor cover from the bottom plate. remove two screws securing the turntable motor to the cavity and take it out.
- The turntable motor
Part number: W10207571 
Here are the breakdown diagrams and
Parts for Jenn-Air JMC8130DDS Microwave - AppliancePartsPros.com
Gene.