I tried to plug my Atari plug-and-play into my LG TV with it's RCA cables, and the video shows up on the screen, but the quality is all blocky and glitchy. It responds to movements by the console, and I have cleaned the RCA jacks. How do I fix this?
If by "responds to movements of the console" you mean moving it caused the problem then the problem could be with the cable itself or their termination inside the Atari PnP itself. Try it on another TV.
The analog to digital conversion and upscaling on the TV could also be at fault but wouldn't respond to movement of the PnP.