As technology has improved over the years, more demand has been placed on all interconnecting cables and connectors. Most high-end equipment and cable connectors are gold plated. One of the reasons for gold-plating is to provide the best signal transmission and to help prevent oxidation and contamination buildup on the surfaces. As some people know, even gold-plated connectors are subject to wear, abrasion, and atmospheric contamination.
Many companies manufacture contact cleaners, lubricants, enhancers, protectors, etc.
Having tried virtually all of them, I can recommend only two options. One is to clean every connection every few weeks with a solvent such as trichlorethane or petroleum naphtha. The second option is to use a product called ProGold, by CAIG Laboratories, the people who have supplied us with R-5 and R100L for many years. According to the manufacturer, ProGold is one of their next-generation products. I have noticed that after a period of time even gold-plated surfaces get dull or tarnish and that when the surface is scratched or worn the base metals become exposed.