The reality is, the stock Colecovision power switch gets dirty over time and becomes increasingly unreliable. Thus, making the above 5 and 12 volt rails intermittent causing unwanted artifacts on screen. Replacing it will give the Colecovision the consistent power it needs!
Open your console in order to have access to the Colecovision PCB/motherboard inside.
Locate the power switch on the PCB, and remove it by desoldering it. Start by removing the solder from the bottom.
Using a pair of male and female old PC hard disk molex connectors, solder the female/male molex to the PCB and the male/female end to the switch. This is easy detachment between the PCB and the switch/case in the future in case of needed repair.
Depending on your switch purchased, you made need to modify the top portion of the case of your Colecovision to make it fit.