When most people think of rubber, a certain sense of softness and pliability comes to mind. However, over time, rubber can get brittle, preventing it from doing its job properly. For example, if you've ever tried to use an old typewriter, the paper won't load properly if the rubber tabs are brittle. Luckily, you can easily soften rubber yourself.
Spray the old rubber with WD-40 or a comparable solution. If possible remove the rubber part and allow it to soak in a small basin of the WD-40 or other product.
Allow the WD-40 or comparable product to penetrate the old rubber for at least 10 to 20 minutes.
Wipe the rubber part or area clean with a soft cloth, until you can no longer see or smell the solution on it. The rubber will be noticeably softer and look newer.
If the rubber in question was noticeably hard or old, you may need to double the soaking or spraying time.