ColecoVision Troubleshooting Help

[samson7point1]

Need some help from the EE types.  I think this one comes down to general troubleshooting, but I'm kind of at a loss.  

The ColecoVision has a Ben Heck composite mod.  It was "working" but the colors were smeary and the picture was generally unfocused and a little shaky.  While I was playing it, I switched it off and back on and when the image came back it was monochrome, but the picture was super stable and clear.

In the process of troubleshooting hand slipped on a probe and accidentally bridged pins 3 and 4 of the J4 (the connector that goes to the RF box), and instead of releasing the magic smoke, it actually brought the color back - and it the picture actually looked fantastic.  Pin 3 is the "R-Y" video signal and pin 4 is +12v.

If I power off the console, when I turn it back on it's back to monochrome.  I was able to duplicate the "accident" using a resistor.  A little trial and error showed that if I bridge the connection with a 100 Ohm or smaller resistor for a second or two, the color comes back.  If I hit reset the color stays, it's only when the console is powered off and back on that it goes back to monochrome.

To troubleshoot:
- Replaced all the electrolytic capacitors

- Rebuilt the power supply (the 5v rails were both registering 4.85v without a load)

Can anyone with a little more knowledge and experience with this sort of thing help point me in the right direction?