OK, what about a larger light bulb?
I find a 150 W PAR floodlight bulb. Now, I get something much closer to normal. A little squashed top and bottom but nearly or totally full width. Go for it! Leaving out the light bulb but still using the Variac, a not too terrible picture appears at about 90 V or so and is fairly independent of input voltage. An antenna helps quite a bit but the picture is still pretty ugly. The vertical is squashed top and bottom and pulsating apparently along with some hum bars rolling up the screen. I let it run for a few minutes and pull the plug. HOT is still cool. OK, so it, at least, is happy. What about that ugly picture. Adjusting V-height and V-linearity are not able to get it full screen top and bottom simultaneously and there is still that pulsing behavior. Well, probably a bad capacitor.. There are only about a half dozen electrolytics in the vertical output stage. Locating part numbers is a bit of a pain with the poor quality copies but the forth one I test reads way low on my capacitor
