[serf]

not parent, but it's often plating related.

The part is made with a specific dimension when plated; the plating wears off -- this produces an undersized spring component and results in a sloppy/loose fit.

it happens more with headphones with a very heavy wire or jacks that get plugs swapped very often.

it can be fixed by carefully using a pick to deform the spring further out, so people tend to think that if that's the case then it must be the spring itself getting lazy.