Submariner Anniversary not changing date

[BrettG]

Hi Guys,
I need your insight - I have an anniversary Sub - which was purchased new circa 2009 & worn sparingly.
This week I noticed that the date will not change - I can alter the date
when I unscrew the crown and pull it out to the date setting. But when it runs normally the date will not change at all.
I also unscrewed the crown to the last detent and advanced the hands 48hrs or so and no change.
Any ideas what is going on here?
Recommendations / referrals?


thanks in advance.