<font color='#000000'>Is it still in the right channel even after swapping speakers? Is it with all CD's? Some recordings will have more bass in one channel than another.
If it stays on the right side regardless of whether you switch speakers and with all CD's and other sources, then I'd say it's an amp problem. But usually, if an amp is going bad in one channel the entire sound in that channel will be noticably weaker, not just the bass.
If you have a bass tone control, maybe it's shot? Or (not to be insulting because I've done dumber things, believe me!) maybe you have the bass tone control turned down on one channel if your amp has separate controls for each channel?
Generally, cables either pass the entire signal or nothing, though I think I've had an interconnect not plugged in all the way that still transmitted a weak signal but it's real noticable. More usually it's either no sound at all or it hums loudly.
All in all, I'm guessing that you've listened to a few recordings that probably just have much of the bass mixed in the left channel.</font>