Welcome to Mitutoyo and their abysmal quality control. It appears to be separation, there's nothing that can be done really. If you pull it apart, you won't be able to put it back with the precision required. Still $60 is a nice deal.
Mitutoyo 20x M Plan objectives have the poorest longevity. 3 of them crapped itself on a friend I know after just 3 years of use on his measuring stuff.
Wish there are better made mit alternatives at similar prices, but unfortunately it doesn't appear to exist. '
Chris S. wrote: It's worth noting that even Mitutoyo reportedly will not perform this service.
Yes, they won't. Mitutoyo objectives are like disposable containers. Hell, some come out of the factory and misalign itself. It's quantity over quality. That's how they achieve the cheaper prices (in perspective).