I have to agree totally with AfxToo! Do not open it until its value is confirmed! One can be of any opinion of the collectors ideas what to pay, but in between the condition you describe and tearing the parts apart CAN be easily a difference of 1000$. Can of course, depending on the rarity and the mood of some few guys out there with the deep pockets....
Maybe ask in the OWH board (http://oldweirdherald.com/slotcartalk/
), in the vintage section. There were the specialist in this field.