The weird fault looks like a shadow, but is something else. When tuned in those areas are completely dark, but with snow it looks like this:
I've heard of the soldering iron trick before, but I think that only works with big AC gun type irons that I've seen, but never used. All of my irons are the low voltage DC temperature controlled type. I've also tried wrapping a couple of deguassing coils from scrapped sets around an old tennis racquet. That made lots of pretty colors, but no lasting results. I've had some success using magnets removed from old hard drives, but that's too much trial and error. If I'd known degaussing wands were only $15 I would have bought one earlier.