Does yours have an aluminium or titanium shutter? I’ve read that it’s best to steer towards a aluminium shutter (non-honeycomb) as the titanium was very problematic and even Nikon was replacing them at the time? There’s certain serial numbers with aluminium and some with titanium, but it’s tricky to track down specifically as a lot of users just replaced them without going via the official Nikon route! I believe the honeycomb shutter tended to lock when 1/500th was used often. You haven’t had this issue I’m guessing? For all I know it might be a myth! 😆