facetime not working, all other cam apps do

odd one 😕

ALL OTHER CAM APPS WORK! ...but FaceTime does not 😠

when launched I get a black screen, seems to be a mild pixelation occurring, but clear as a bell in the lower right corner, in reverse. It counts from 0-9 continuously.

I've tried PRAM zap, reboot, shutdown/startup

I've tried killall VDCAssistant and killall AppleCameraAssistant

worth mentioning this iMac has recently returned from a logic-board replacement, following total video failure

Any way to dump prefs from FaceTime only?

once again, ALL OTHER CAM APPS WORK! Quicktime, Photobooth and...

SKYPE:

Interesting discovery in Skype, when launched it was set to use Camera GENERAL UVC and I can see

a reversed date and time, counting!

if I change the camera to FACETIME HD, the cam works fine.

So how do I change this setting in FACETIME?

TIA