I received some molds that are old and it seems some have not been used in a long time. Some are breaking. Are old molds usable, or should I dump them?

I received some molds, very beautiful, but they have not been used in about 5 years. I am told they no good because they were not been used for a long time. Some seems OK but some are breaking, and the clay is taking a long time to dry in the molds I am attmepting to use. Can anyone comment. e.g.. Tell me from experience if I should just dump them.