First off, my apologies if this is posted in the wrong place or it has been answered before; searched the forum and came-up empty. Anyway, cleaned out a drawer last week and found this Seiko I forgot I had. The numbers on the back are: 5M42-0C39 and 501613. The watch is working, but is not holding a charge overnight; as long as I am wearing it, it keeps time perfectly. Anyway, just wondering how old it is and what value, if any, it may have. Was thinking of gifting it to a nephew.