maybe consider lubricating it? If you have some CRC556 or WD40 you could try a tiny bit to see if the noise goes and if it does work then put in a tiny amount of machine oil for long term? May be easier than replacing the fan.

It is better to use light machine oil (sewing machine oil) on fans than the spray on stuff which will not last long.  Do not use 3-in-1 oil (vegetable based) as it tends to attract dirt and dust and clog up.  Fans that can be lubricated have a cap over the bearing in the centre of the fan.  This can be an unclippable piece of plastic or metal, but more usually is just a sticky label that you can pry up.  In well designed equipment it will be on the top of the fan, but sometimes they are mounted with it on the underside.  If you can take the cover off and see the bearing, just add a drop of oil and cover it up again.  Unfortunately, there are also a number of fans where there is no good access to the bearing, in which case you can try a penetrating oil to see if any can get in, but even if it does it will only be a temporary fix.  With the ones you can open up, if you oil them regularly (every year or two) before any noises or slowdowns happen, they will last a very long time.  Once a bearing becomes noisy, it will have already suffered some damage and will not then last so long.