There are a few things here. The bracelet has several areas that will likely need to be addressed. The first is if the links themselves are loose and sloppy, the pins and tubes in the bracelet likely need replacing. These can come loose, as you can see in the photo below - test them on every watch that comes in and often there are some that are loose and easily pushed out:
The sleeves wear out over time:
As do the pins:
In severe cases, the links themselves may also be worn:
So replacing the pins and tubes will often solve that issue.
You don't mention what part of the clasp is problematic, but often the clasp springs need replacing - there are different types, but this is one common style:
Just replacing this spring inside the clasp made this clasp go from falling open easily, to being very secure - it's a quick fix and the new spring isn't expensive.
The next thing is the dive extension. The extension typically looks like this:
The gap between the two ends of the extension is different, so the first thing is to open up the left hand end as much as you can, and that alone may restore the extension enough so it clips in securely. But if not, then the small tabs can be staked:
A staking set is used for this:
Couple of taps, and the problem is gone:
My advice would be to seek out a watchmaker with an Omega parts account, who will be fully equipped to repair your bracelet, and also order the parts needed directly from Omega. If needed, they can also order you a new clasp, or entire new bracelet as well.
Cheers, Al
