Sound Interference on the2600 Jr.

[Zeus]

I recently bought a 2600jr at a garage sale for $2. It works fine except for the fact that there is so much audio interference that it completely overrrides any sound fx. Anyhow, the system seems to work fine otherwise. Is there some sort of built-in flaw with this system or is it just the ravages of age? The sound on my Vader is just fine. What gives?