Electric Hair clipper problem?

I bought an Electric Hair clipper for 25 bucks and been using it for 2 months. recently while i was cutting my hair, the clipper suddenly started to make noises. like lawnmower noises. on the manual there's a screw type thing that you can adjust by a screwdriver. so i adjusted it but the noise won't go away. and worst it's not cutting my hair anymore. what could possibly be the problem? is there someone who could teach me how to D-I-Y it?? thanks a lot.