I've got a little Philco tube portable, the one with the roll-top dial cover. It oscillated. By some wild guess, I tried a grounded tube shield over one of the tubes--can't recall if it was the converter or IF amp. That solved the problem. No idea exactly why but since it worked I stopped thinking.
And I'm not one to pay much attention to snooty evaluations. If I find something and it's cool in some way, I'm happy enough. Lots of my radios are kept because I remember who gave them to me, or where I found them. A few are those little table radio TRF sets with 4 tubes and a big ballast resistor to drop the series-string filament voltage. They were designed for local listening. Sophisticated? No way. Exotic? Are you kidding.... But they tell us something about marketing, and cost control via component reduction, and even a bit about '30s and '40s style. One that I pass by every time I walk in my back door was given to me by Shirley Leibrand, a neighbor lady when I was a kid. She was, of course, Mrs. Leibrand, not Shirley. Later in life she went into the antiques business and handled estate sales, and from one of those she plucked the little TRF set because she thought I'd like it. It always reminds me of her. Your Zenith conjures up lots of memories, too, doesn't it? That's a good enough reason to own it. And if your wife likes it, so much the better.
Chris Campbell