Okay, new power supply came in--Colecovision's started breathing. Channel 4, lots of static, but the game is clearly playing in there. Perhaps a power switch issue.
I use the gold barrel adapter and Atari RF wire for mine. If you have an Atari switch box with the switch on top that slide either to TV or GAME should work since auto switchbox like the NES RF box only work halfway and will show snow.
I'm going to hit it with some contact cleaner and see if that helps. I've also got a replacement switch on order just in case. There's way more static than game displayed on the screen. I'm not using a switchbox, but the rf cable looks old so that might also be part of it.
I don't think I'm going to video mod this one (yet). I've never played the system yet, so I'm not exactly 'in love.' Also I've noticed that composite mods don't tend to look stellar on this system.