Fans are such an important component when it comes to your 3D printer. Over time, they will clog up with dust and fine strings of molten filament and become less effective. It is a good idea to keep them clean by using a small paint brush. These are classed as consumable parts and will need to be replaced at some point. Bearings wear out, magnets become weaker and the fan just can't do its job of cooling components efficiently enough!
If you have issues with your fans, chances are, we have the exact fan you need, or one that will fit! Dont let your printer overheat and cause more damage, just grab a new one!