Fixing old stereo amplifier (crackling potentiometer)

This video is simple and general instruction how to fix one quite common problem of stereo amplifiers, the crackling potentiometer. I explain how potentiometer works, why it may cause crackling sound, and how to fix that.
Device I'm working on, is Yamaha, but most of the 80's and 90's amplifiers have similar type of design and basic components.
Side note:
I'm a mechanical engineer, but what it comes to electronics, I'm mostly self-learned. Do not try to fix your electronic devices if you're not sure what you're doing. If you handle electrical devices carelessly, you may get electrical shock or cause malfunction to the device.