Remove the 11 screws that hold the assembly together.

Use a soft brush or compressed air to clean the heatsink fins and fan.

My fan was making a grinding noise so I unpealed it`s back sticker carefully and used just a tiny drop of sewing machine oil from a needle to fix it. Then reapplied the sticker to keep dust out.

When putting back the cooling assembly, do NOT tighten the screws a lot, because the base is made of plastic and will break.