Looks like my turn to put the useful posts above to good use.
About a week ago my 2017 started having a bad image with fluttering noise when I backed out my garage and then when I arrive at work it would be fine and when leaving work it would be fine - an intermittent issue which usually occurs the first time its used in the mornings.
I'm suspecting a bad connection so I'll pull the covers off and inspect connectors and add dielectric grease where needed, and search for moisture ingress - if all that fails I'll look at a replacement camera.