Cleaning of SNAIC cable and DIN TO RCA

Having routine cleanup of my system, I noticed that my SNAIC cable connecting pre and power amp, the pin inside the plug have gone black due to high air pollution in Mumbai city. The same thing happens to DIN TO RCA interconnect cable. It is very difficult to clean DIN plugs.
How to remove this carbon from the plugs? Can I use contact cleaner? Plugging in and out frequently does help temporary.

The pins should self clean with repeated plugging in and out. If very bad then you might also try cleaning the pins with some Isopropyl alcohol or methylated spirit. Avoid anything such as contact “enhancers” that may leave a residue behind - you may feel these work well short term, but in the longer term they may well cause problems.

The blackening of the pins in DIN plugs is likely to be Silver Oxide, as the Pins are probably Silver plated.