Older Pioneer help please

[mopar4u]

Pioneer RX-531 rack mount system, probably pushin 15-20 years old, never had a problem til now. I've always thought it was a great system, over the years it has been demoted to the garage stereo. Anyways, this winter the sound would come and go (without touching the volume), sometimes the sound would go really soft, but you could still hear it, sometimes it would comepletely go away. This happens with both sides. If you tap the chasis the sound comes back on for a while then it repeats. Pretty annoying . I realize it is old and not worth putting much money into but any suggestions on how to troubleshoot? I'm not afraid to take the cover off and dig around. What should I look for?

[Elvis R]

It may be a corrosion in the potentiometer (vol ctrl). Try some electronic spray on inside of the control. It cause also be lose soldered connections. Gotta use the good ole eye for that.