That's the problem. It depends on the polymers used. Without knowing more,.only general answers can be given . For example, it could be continued crosslinking, it could be loss of plasticizer, you get the idea. As a first pass, you can try putting a drop of mineral oil on an unused part of the device. Work it in. And give it some time. It.may or may not work. And it may or may not work on all of the parts of the electronic device. For example, one part maybe made of black rubber, where it might work. On the other hand, a drop of mineral oil on some plastics might not work. It depends on the type of plastic or rubber. Also note that sometimes they can be dissolved by oil. Not likely,.but be careful. That is why you should only go a small drop at a time.