I didn't know DuMont invented them. That must be why they still used them in my TV. Is the variable tuner a unique feature of the DuMont sets? I don't remember any other set being like the one I grew up with, they all had click dials.

I once owned a Dynaco FM-3 tuner that had a variant on the eye. From what I've read on the Dynaco Doctor forum these tubes are impossible to find. I wonder if the version the DuMont uses could be adopted to use, although the eye on the Dynaco IIRC is a horizontal mounted tube, and the eye on the DuMont is at the top.

I'm just glad mine still works. Even the side mounted dial lightbulbs still work. I'll be surprised if the picture tube is bad. My guess is a cap blew at some point and the grandchildren just figured it would be cheaper to buy grandma a new color TV, it was around 1985 after all.