 Hi, I bet you’re talking about cleaning RCA contacts such as the pin.
You may wish to try the XLO “TPC”. This is a small piece of wipe heavily soaked with certain solvent that come in a small pack. Very users friendly and inexpensive. Should be about a few $ per pack. One pack should be enough to clean all contact of an entire audio system. This is a ‘Stereophile’ recommended product if I’m not wrong. Check out with Audio Suite. Alternatively, you may try products from Craig such as ‘Pro-gold’ and ‘De-Oxit’. The former is for regular maintenance and latter to remove oxidized contacts. There are 2 spray can packaged ‘Pro-gold’ with different concentration: 100% or 5%. The former is about $60 a can and latter $40 with a bigger can. Check out with Electrades. Hope the above helps. | 
