[drh4683]

Greetings & congratulations on an excellent find! I don't think I've ever seen a Zenith CRT with a line etched into it from loss of vertical sweep. Someone must have cranked the G2 controls and left it like that for a while for that to happen. Certainly replace that filter cap if it's warm to the touch. I can almost guarantee that the reason the space command chassis is dead is because of a particular electrolytic capacitor in the power supply of the space command chassis itself that has failed. If I remember correctly, the Space Command 500 circuitry is mounted on a PC board within that metal sub-chassis and somewhere toward the middle of the board is the very small radial 'lytic with a value of about 10uf @ 3 volts which is the suspected culprit. I've had a number of these sets over the years and with every one of them, that cap was the reason the space command didn't work. The last time I had one apart to repair was 10 years ago, so thats why my memory is a little foggy. The other caps within the space command chassis are probably OK as I think they are a different brand that held up better. When that 10uf cap fails (due to high ESR) it's basically an open circuit and you lose collector voltage on all the transistors which is why everything ends up being dead. You shouldn't need to align anything after replacing it. It's a nice quick and easy repair.