I'm not sure if this is a common problem but it seems to be with my limited exposure to 70s receivers. I purchased a Marantz 2252b and cleaned the heck out of the pots and I still had this requirement to increase the volume to prevent the fade out of one channel (right in this case). After searching a bit, I cleaned the speaker relay with small strips of business card paper/deoxit and that did the trick. This segue to the KR-9600. After restoring the power amps, power supplies/resistor mod and switch mod, I still had a similar problem with the Kenwood. At low volume, one channel just kind of fades out (again right channel). So I replaced both speaker relays with new ones and that again took care of the problem. I guess from reading, these relays after 40 years tend to wear out, too? Although, I've also read, they are one of the most reliable parts. At any rate, they're insidious in the way they creep into some of the problems that crop up.