Panasonic B&W small tv problems

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Here is a Panasonic I am not sure where to start on. When powering up the snow does not fill all the screen, and the whole picture is jittery. When I hooked up a Nintendo Entertainment System the screen formed lines but would not show a proper picture, just bars across the screen.

I know from past experience that a screen that does not fill up means bad caps, but I am not sure how to deal with the other issues.

This tv came from the local recycling center. Every other day I go and grab up any vintage TV I see. Here in rural Tennessee there are plenty of these little tvs but the issue is at this center they sit out in the weather. Maybe this caused some sort of damage? I have dumped water out of TV's and then used them, so maybe not.