That sucks. I bet the metal spring is moulded into the plastic. Or installed in such a way they can not be removed.

Have to tried a product like CLR. Or even soak in Vinegar for an hour or so. Vinegar works well for removing light battery corrosion on mobos. I use it often. And its dirt cheap.

On another note, I do have a spare set if interested. I have an almost complete portable that I have been parting out.