Usually in situations like this, I would remove the fan and look at the sticker on the back, it should tell you the name and model type of the fan.
Also measure the fan diameter and the mounting hole spacing, in millimeters.
Then search ebay, aliexpress, or your favorite search engine for a cooler fan that matches either the fan model, or the size and mounting pattern.
But if that fails, you can try extending the life of the current fan by cleaning it out thoroughly with isopropyl alcohol. Then peel back the sticker, and add a few drops of machine oil to the shaft bearing.
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