want to fix nutone Im 4006 intercom/radio

I moved into a home with the IM-4006 series Nutone intercom and Ir-103 rough-in frame. Since the system was not working - no power - tech support said to replace the power transformer. After I did, the situation is the same - no light appears on the radio light and nothing works. Can anyone help me with providing the circuit diagram for the IM-4006 and or any useful suggestions on how to repair. Thanks RK

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