Zenith System 3 Help

[maxm]

I have been trying to help an elderly friend of the family with her Zenith System 3 table top 13" set from the early 80s (1982?). It is a Space Command set with on screen display.
She would like to be able to have this set working because she worked for Zenith in Chicago for over 30 years, and therefore the stuff she has from Zenith has sentimental value to her.

The problem with this set is that sometimes it will not turn on. It you hit the top of it (think Onslow on Keeping Up Appearances...maybe I'm the only one who watches that show...), it will usually turn on. Other times, when you try to turn it off, the screen will go blank and the sound will cut off, but the electronics will stay on - the CRT filament is lit and you can hear the flyback running.
Twice I have tried to take the set apart and clean as many as the connections as possible, thinking this problem was due to a bad connection somewhere. This set is full of wires connecting the different boards.
This seems to make the set work well for about a month, then it goes back to the same problem again.

I know that problems like this are probably very difficult to solve, but I thought the fact that it does not always turn off completely might narrow it down and somebody could offer something specific to look at.
I'm sorry I don't have more pictures of the set or a model number, it is not here right now, but I will probably be visiting the owner over the weekend, and can bring it home to try to get it going again if anybody has any suggestions.





Thanks,
-- Max