Gritty Sand in AF ring on 70-200 f/4 IS L

I've managed to get a very small amount of gritty debris in the AF ring on my 70-200mm f/4 L IS.

When I manually focus I can occasionally feel the slight "unsmoothness". Is there a way to remove myself ?
Any idea what Canon service might charge ?

Thanks ahead of time for your answers/help.

I thought about hooking up a shop vaccum to a small aperture hose and trying to create high suction around the ring ...

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