Can't adjust microphone volume

A few days ago this PC was in the current state:
Microphone on USB camera set as primary recording device - the volume of the recording can be adjusted.
Onboard soundcard was being used for sound output (but something seems to have blown in it as sound was always very quiet).

After inserting a new soundcard and disabling the onboard soundcard in the BIOS, the new soundcard is detected and configured correctly. Primary output device is the new soundcard, primary recording device is still the usb camera. However, now the volume control for this microphone is grayed out and can't be adjusted. Any ideas?

 

Try reinstalling the drivers/software for the camera.