My Atari 7800 produces a terribly fuzzy picture on my TV. It is equally bad for all cartridges. I would describe the picture as "barely playable", and certainly several notches below "enjoyable". I recently bought a new manual RFU switchbox when a wire on the original one broke, but that hasn't helped matters. I have tried all combinations of channel select switch positions combined with setting my TV to channels 2, 3, and 4. However, because a local station broadcasts on channel 3, I can not use 3 for the system. IIRC, channel 2 is the one that is usable.
This unit was sitting in a garage for a few years, so should I suspect corrosion on the pin connectors? And if so, can I swap in a new set like you would do on a NES? Or is it possible to use rubbing alcohol and some sort of swab on the console?