We had been getting some interference (heavy snow) at odd, non-predictable times on our TV (old, analog type). I tried turning the antenna, turning off various things like the fridge, plug-in fans and heaters, etc etc. After a couple of years of head-scratching, I just happened to be watching a perfectly clear station when the SO turned on the over-sink fluorescent light fixture and the picture went bad. DING, the mental bulb illuminates and the "problem" was at least isolated. Bad starter I am guessing.
That's my story and I'm stickin' to it.