I've been having problems with the balance on one of my stereo receivers for about a year now, and hopefully someone here has experienced this and knows a simple remedy.
Simply put, the left-channel speaker output is higher in level than the right. If I crank the balance control about 40% towards the right, I get a properly balanced stereo signal. The line outputs on the receiver (such as the tape output) do not exhibit this problem, and the problem happens when the receiver is set to any input, including the internal radio tuner.
None of the controls sound dirty -- the volume control is as smooth and clean as ever, as is the balance and tone controls. The receiver is a little over 12 years old, a Sony STR-D311. It's a pretty plain stereo receiver, but it's treated me well since I got it new. Here's where you can download the user manual for it: http://esupport.sony.com/perl/model-find.pl?mdl=STR-D311