I plan on changing when the 2-seconds jumping warning happens, thankfully the battery is still ticking strong. I've seen reports from a few Tuna owners of some lasting well beyond the stated 5 years, longest I've seen was ~10 years, so it might still be a while. But when that time comes you can be sure I'll be frantic in my search for the best hands, whether that's going the independent route, e.g. Spencer Klein, or Seiko service center route, e.g. NJ, is still to be determined.How do you find changing the battery on them?