There are lots of ways to make the kit that you invest in for climbing last as long as possible, but you also need to know when it's time to retire that beloved bit of gear.
If you have climbed near the sea, and this even included Llanberis with the wind from the right angle, your climbing kit will have been exposed to salt from the sea. Not so much an issue for your soft gear like rope and slings, but can be devastating to metal like Krabs, nuts and cams.
If the salt can get into the metal through the anodized coating via a scratch then, if left alone, it will corrode the alloy and bits of krab will just start pealing off.

This image shows corrosion from salt water on a krab
To prevent this from happening to your kit, just rinse it in fresh water after contact with a salty environment and allow to dry at room temperature.
Checking your it for this kind of damage is easy, just visually inspect each piece as you are cleaning it, but be careful, the corrosion "blistering" can create sharp metal splinters - you don't want these stabbing you in the hand as you check.