[Simon / APP Team]

Hi.

You need to check two things:

First check if the slot in the middle of the support is intact

Part number: 5304440284

Then using the multimeter check if there is 120VAC to the turn table motor when the microwave is ON.
If the proper voltage is present - replace the motor

Part number: 5304440021

Here are the breakdown diagrams and Oven / Cabinet parts for Frigidaire FMV156DSB - AppliancePartsPros.com

Post the results.

Simon.