I get a strange amount of people who want batteries changed in their wrist watches... as soon as they see my pocket watch. Usually nothing exciting. Sometimes a cool Seiko or something like that, but this one took me by surprise. As soon as I saw it, I flat out told him that I wouldn't touch it.. but it's a personal friend and I agreed to change the battery. I did, and after giving it the little accutron love tap on the side it ran, for about 5 seconds. So it was returned this morning with a note and a business card for someone who really knows these pieces. Also included was a strong suggestion to change that lug eating expansion band. I really hope he gets it repaired, as he is the original owner! It's an impressive piece of gold and engineering! So anyways, I wanted to post some pictures just for fellows to see, and ask if maybe anyone knows what model it is. I spent a few hours searching over the weekend and haven't seen another quite like it. Any information I can pass on to the owner would be appreciated! Or if someone could point me in the right direction, I wouldn't mind learning a thing or two about these great watches. Thanks for any consideration! I did not take the back off, apologies. I'm really not a fan of messing with someone elses gold watch! The battery cover was already beat up. According to the M1 date code, I've learned it's from 1961, so a pretty early piece!