All electrical connectors are inherently imperfect and gradually develop and cause oxidation. There's no question that the sound of your system suffers as a result.
Kontak is an advanced cleaning solution (CFC-free) originally developed for military applications. It completely removes all traces of contaminants on any connecting surface, and greatly enhances signal flow. Benefits include improved bass response, enhanced low-level detail and transparency and a greater sense of dynamic range. The more connections cleaned with Kontak throughout an audio/video system the greater the result.
Try it. You'll be amazed.
The old glass bottle held 25ml fluid, the new aluminium bottles hold 30ml