Buyer took out a part after receiving item, then claims item not as described opens claim

[Jeff12345]

Hello,

What can i do as a seller when the buyer has taken out a part of a DJ mixer (crossfader) and claims its missing.

Im 100 % sure that the mixer was not missing any parts when i shipped it now i have a claim against me for over 200 euro. In the pic wich he sent to me on the right corner you can see the original Vestax crossfader wich he claimed was missing.

Jeff