Its one of things you can find when working with natural materials such as wood.

Storing these sort of kits for any length of time can also cause some issues with changes in temperature and humidity.

The nails i would not be to concerned about but in terms of the wood strips would you be able to use them if you soaked in warm water to make them pliable. A wet plank can be coerced into all sorts of shapes and when dry retains the shape.

If things are really bad you could try customer services to see if they can replace the faulty packs. And while not ideal if you have already paid out money you can get these basswood strips fairly cheaply from numerous sources.

If you are able to post some pictures then please do as there is a wealth of knowledge on this site and usually some good resolutions to kit issues surface.

Tony