Eric,
I had a Sears Silvertone 21" color roundie (RCA CTC12 chassis, I think) in the early '70s. Metal cabinet, weighed a ton. Had to get rid of it in '73 when the video output tube socket broke out of the signal circuit board; tried to replace the tube (6AW8) one day and pushed just a bit too hard on the socket. Was rewarded with a sickening crunch as the socket (with the tube in it, if memory serves) fell to the bottom of the cabinet.
Never did get it working exactly right while it was operational, though; the convergence was always way off, and I was trying to adjust it by eye, without a generator, but I was just starting out in color TV at the time and didn't know that much about what equipment was needed to reset convergence, etc. Believe me, when I bought my first new color set (Zenith) in 1979, and every TV I've had since then (including my 1995 Zenith 19" in my bedroom, and my 1999 RCA XL-100 19" in the living room of my apartment), I kept my hands out of the insides of them!