Something catching the fan?

I’ve had my new Drobo 5N for two weeks, and when it is turned on, or comes out of spindown state, I can hear something catching the fan.

I’m sure it’s the fan, because blowing in the rear vent makes the noise go away. If I wait, it goes away after a minute or so.

I don’t want to invalidate my warranty, but is it easy to get inside, to see what’s catching what? My main concern is that anything catching the fan blades is likely to generate fine metallic dust, and that’s not something you want inside.

This is the third Drobo 5 I’ve had since December 19th… the first two were 5D’s, but I kept getting USB3 problems and had to return them. So when the 5N arrived, complete with tinny “sawing” noise, I was rather depressed. But now it’s installed and working, I’m loath to go through the replacement process yet again.

So, I wrote to the seller, informing them of the problem. This means I can get a free replacement should this problem get worse.

But, I’m sure that it would be a simple fix, once I’m inside. It’s probably a tiny piece of packaging that found its way into the fan area, or perhaps a slightly bent fan blade.