Why is there a rattling sound coming from the cooling fan

every time i come to go to youtube netflix or even play on games there is a rattling sound that arises and i checked the heat sync fins and found what appears to be either a small bit of plastic or fluff and nothing else so what could be causing it as i did check the cooling fan itself and it does not seem to be rattling to so what is the cause of this issue

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While you have the cover off, maybe take a good, clear photo and post it here.

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To add: You can also put a video here, so we may recognize the sound!

Thanks!

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@dan0 I did a video but whether or not it will be shared will be the case

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