Synology DS918+ Hum

[Vectraat]

My NAS works great, but over the past few years It's started to hum a bit.

I've attached a video so you can hear what it sounds like.

Keep in mind, my phone camera is almost directly up against where the sound in emanating from so maybe it sounds louder than it is.

If the room is silent I can hear it hum from maybe 11-12 feet away, but It's not that bad, just mildly irritating. The NAS doesn't always produce this humming sound or maybe it does but it's not as loud so I don't hear it.

I'm wondering if perhaps something is lose with a fan or the side panel. (The screws don't look loose). When I very gently touch the top right or top back right of the enclosure I don't hear the humming sound anymore until I release my finger. Should I be trying to tighten any screws somewhere? Is this a fan issue?

[Vectraat]

If I place my finger on these areas, the sound stops (until I release).