Thanks so much for your help.
I believe that I am unlucky. If I reinstall FCP will the effect return? Also, just to cross my ts, if I reinstall FCP, none of my video files/projects will suffer, correct?
I’m so sorry about the long delay in responding to you. It turns out that my issue was related to how long/hard my hard drive had been running, ad a quick reboot/moment of rest restored any image quality issues. I was also experiencing a lot of dropped frames. Hope this helps.