Problem with my Sylvania TV

[wa2ise]

My brother tells me that this Sylvania set:

has developed a problem. Namely that the deflection has collapsed to a small image, like 3 inch by 3 inch. He also heard some popping noises. Obviously, this picture was taken when it was working well.

I haven't seen the set myself, as I'm in Seattle and he's in NJ. Anyone familiar with Sylvania sets of this vintage? I'd guess that something has failed in the power supply feeding the deflection.