I have read that the flyback transformer in the Color Classic was slightly undersized to began with.  And then, because of venting issues, it became slightly hotter then it would like to be. You add both of the above together, then increase the voltage from 60V to around 68 or 69V, on pin 8, and maybe you are asking for trouble.

I suspect I could find 12V someplace on that analog board, and mount a very small fan next to the flyback transformer. 

But I know more about brain surgery then flyback transformers.

Can anyone here recommend a more robust flyback transformer that I could swap out with the one on my Color Classic, slap a micro fan next to it for good measure, then move ahead with the VGA mod?

What other crucial components could be effected when the voltage is raised?

Thank you for your very interesting post. 

jack