I've been authorized McIntosh technician for over 35 years. I hade my fare share of rebuilding vintage McIntosh equipment. I just love C20 model and I restore many of those.
Very beautiful sound, very bright and detailed. But, very common problem with C20, and I would say every one of them. Is a defective volume control.Ether broken switch, not very common, or uneve. Stationary carbon composition resistance elements because of aging. In the results you would have unequal channels, or no sound one one or both channels. By replacing volume control with my new one, you would not have that problem anymore.
I will include some pictures of restored McIntosh C20 in the listing just for reference only. The item "Volume potentiometer pot control power switch on/off McIntosh C20 Pilot SP-210" is in sale since Saturday, November 30, 2019. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Parts & Accessories\Other Vintage A/V Parts & Accs". The seller is "sewing-pro" and is located in Chicago, Illinois.
This item can be shipped worldwide.