@Techlover
You Can Find Them at Katranji
http://www.ekt2.com/products?cat_id=4f5e84f1-2613-4365-90d1-7bc59571d06e
but Yes as "Rolf" mentioned dissembling the fan and cleaning/oiling it will increase its lifecycle , but you need to know how to do that and reassemble it. If you are a 1st Timer and willing to do so, skim through YouTube there are many videos illustrating that.