Korg LP-380 key cover closing loudly

I recently bought a Korg LP-380 U digital piano. One thing that keeps bugging me is the key cover: it’s supposed to close softly, but I wouldn’t say it does. While it’s visibly slowed down by the mechanism, it still makes a fairly loud “clack” noise once it hits the end position.

I’m unsure if this is within specification or if I can adjust this myself. Wonder if there is a service manual out there; I’ve googled quite a bit but could not find anything.