I recieved this watch in an auction from an estate sale. I do not know watches at all and not sure if this is worth keeping or selling. I cannot figure out how to open up the backing to see the inside. There are no buttons or anything and I am very nervous about prying it open. I have tried numerous times to find information about Oris vintage watches and there doesn't seem to be much information out there, at least that I can find. Can you please help me date this watch, price, etc. Thank you for your time.