[0nly5iv3Digits]

It's the pins that hold each subsequent link together. They are made of thin steel (essentially like a spring-bar). They bend over years and years of wear, particularly when the watches are worn loose and left to "flop" around the wrist. The "top-heaviness" of the case puts a lot of strain on them.

Easily fixed by the right professional. Just needs to be re-pinned throughout.