HELP! broken extractor fan, how do I fix?

[plusonemore]

Its the hob one. Well its not completely broken, it works on the top setting but its so bloody noisy that I cant stand to have it on! Would love to be able to use much quieter 1 and 2 settings but they just stopped working one day

does the filter need replacing?

Has the bearing inside the fan broken, does it need oiling, is the fan blade striking the casing of the fan housing?

ooh interesting questions!
filter was replaced recently, it works on the highest setting so would the other things stop the lower settings working? sounds normal when it works on the high setting (although so noisy, but has always been so)

I suggest you take the filters off and look at the fan as it is going round (if safe to do so). If it works properly with no noise without the filters then I suggest it was hitting the new filters that might have been put in wrongly.

Look for vibrations and damage to the fan blades or even the fan just wobbling on its axle. That mightcluses as well.

We have a bathroom fan that does this.