I'm having a screen flicker issue with a Panasonic Plasma TV hooked up to a Sony receiver. The issue is intermittent but common. The flickering is a white flash that lasts for a fraction of a second and repeats every 3 or 4 seconds. It happens both from cable and streaming. I have replaced the receiver so that is not the issue. The HDMI cabling is long and tortuous so before I go and start that monster job I'd like to know if there is a possible other culprit. Thanks. The TV is 8 years old and I have not had any issue until recently.