The left hand door mirror has been rattling for a while. A search of the Corvette Forum soon provided the answer.

It’s an easy fix, but pictures always help.

The mirror is held onto the motor by three points – the trunnion which is a mini UJ in the center, the threaded motor rod on the outside and a pivot at the center bottom.

It’s clipped in. With fingers behind the glass mirror it can be gently eased out of it’s clips. I wouldn’t be surprised if the thin trunnion broke, or the clips fractured so it’s worth being very careful. Mine were held in very stiffly but I had no problems.,

The motor is held by 3 screws to a frame and it was the frame that was loose and rattling.

I removed the 3 large screws holding the motor onto the frame- circled in yellow.

Once the motor was removed I could see the 3 screws holding the frame and they were all loose. I removed and cleaned them then retightened them

Pressing the mirror back into it’s clips, especially the top of the trunnion, required more force than I expected. All went back OK and no more rattling noise from a loose door mirror.