iPod Video 5.5 headphone jack piece fell off.... Any ideas if I should replace?

[SubparHans]

So I have a Rockbox'd iPod 5.5.  It is great.
Today I noticed a piece has fallen off the headphone jack.  It seems to be the black part underneath the jack which can be seen on the below image:
https://eoe.works/cdn/shop/products/IMG_3779_1024x1024@2x.jpg?v=1597145720

Any ideas if this is important? It still seems to play music.
I can't really do A/B tests to confirm if audio has degraded in any way.
What is that part anyway?
Would it be worth replacing the headphone jack to be on the safe side that my listening experience hasn't degraded.

Any info would help me.

Cheers.