Receiver problem - one channel sounds weak

I have a NAD 7400 PE stereo receiver (late 80's) and I've recently noticed that one side is louder and sounds "fuller", with the other sounding weaker (switching the balance between the two sides). This happens with both speaker settings (A and B - different sets of speakers, so I know it is not a speaker problem), and regardless of source (CD/video/tuner). Not sure how long this has been happening. Does anyone know of a potential cause and/or solution? I like this reciever so I hope it's fixable. Any help is appreciated!

My best bet is that the weaker channel may be going out, the cause of this I don't know but I am sure others will. The left channel on my rotel 1080 went out after 1 year. Obviously you are not under warranty, but I would contact your dealer and as in most cases you will find the problem is fixable. :6:

Did you swap the speaker wires to see if the problem moves?

If so - yeah, it is getting ready to fail. :( sorry.