It appears neither my inner rearview or outer mirrors are dimming anymore. Any ideas on how to correct?

 

You have it turned on right? Button on rear view mirror.

 

Yes - the light is on.

 

It uses the light sensor mounted into the mirror to detect the glare of headlights. I would next see of you can test the sensor. Did you recently install any window tint or have any other obstruction that would prevent the sensor from working? From light hitting the sensor from rear headlights?