I've been searching on google but couldn't really find anything, probably since my watch is pretty old. My 1978 Rolex Oyserdate Precision loses about ~2 minutes over a period of about 36 hours. It has a manual winding mechanism and when it runs out (when I don't wear it for a few days and forget to wind it) it's off by a minute or 2. I think it goes for about 36 hours or so, certainly no more than that. Is this normal or does it need servicing? Also, if anyone here has any experience with Rolex servicing, how long will the watch be gone for and how much can I expect to pay? Other than this it's in perfect condition.